rus
Issue #7/2024
D. N. Artemiev, N. V. Latukhina, A. A. Melnikov, D. A. Nesterov, M. V. Stepikhova, E. Kh. Khamzin
Structure, Composition and Luminescent Properties of the Oxidized Porous Silicon Doped with Erbium
Structure, Composition and Luminescent Properties of the Oxidized Porous Silicon Doped with Erbium
DOI: 10.22184/1993-7296.FRos.2024.18.7.540.548
Structure, Composition and Luminescent Properties of the Oxidized Porous Silicon Doped with Erbium
D. N. Artemiev1, N. V. Latukhina1, A. A. Melnikov1,
D. A. Nesterov1, M. V. Stepikhova2, E. Kh. Khamzin1
Korolev Samara National Research University, Samara, Russia
Instituteof Physics of Microstructures of the Russian Academy of Sciences, Nizhny Novgorod, Russia
This paper is devoted to the study ofluminescent properties of porous silicon doped with erbium. The development of semiconductor materials activated by the lanthanides is a vital task of contemporary physics and technology of optoelectronic devices. The object of research is oxidized porous silicon doped with the erbium ions. The structural and morphological analysis and study of the luminescent properties of luminescent structure samples based on the porous silicon doped with erbium have been performed. The studies have been carried out by the methods of scanning electron microscopy, Raman spectroscopy and micro-photoluminescence spectroscopy. The analysis of samples has demonstrated a correlation between the process parameters of the produced luminescent structures and efficiency of their photoluminescence. The results of studies can be used as a basis for the production method of silicon luminescent structures for optoelectronics.
Key words: porous silicon, rare earth elements, erbium, scanning electron microscopy, micro-photoluminescence, Raman spectroscopy.
Article received:07.06.2024
Article accepted: 29.10.2024
Introduction
Porous silicon (PS) doped with erbium attracts attention as a material on the basis of which an efficient IR LED on a silicon substrate operating at the room temperature can be obtained. The development of such a device will allow a transition to the completely silicon optoelectronics that will significantly increase the capacity of all data processing systems, their speed, interference immunity and other parameters. PS, as a system of nanocrystals, provides an efficient mechanism to transfer the pumping energy to the luminescent centers connected with the erbium ions [1, 2]. The nanocrystalline silicon systems with erbium are of particular interest since the Er3+ ionprovides a narrow temperature-independent spectral response at a wavelength of 1.55 μm that corresponds to the spectral window of quartz light guides [3, 4]. In addition, in the systems with erbium ions, the up-conversion phenomenon is observed that allows converting the near-IR radiation into the visible light. It can be used to develop the up-conversion coatings for efficient silicon solar cells [5–7]. In [8], it has been shown that the intense optical pumping of silicon nanocrystals can lead to the inverse population of Er3+ ion states, resulting in the necessary condition for optical amplification in these structures. In this regard, the studies of PS luminescent systems with erbium are of great interest. It has been shown that the luminescence efficiency in PS can be changed by introduction of certain impurities [9–11] or by special material treatment to prevent erbium clustering [12, 13]. The studies with the scanning electron microscopy and Raman spectroscopy methods have also made it possible to determine a clear dependence of the luminescent properties of porous silicon on the dimensions of PS nanocrystals [14]. This indicates the crucial role of the structure and composition of the erbium ion immediate environment in the luminescence signal generation. Thus, the review of conducted studies demonstrates the importance of structural and morphological analysis of luminescent systems with porous silicon and identification of the most important parameters efficient for the luminescence excitation mechanisms. In this paper, the erbium distribution in the porous silicon samples with a textured surface that is conventionally used in the silicon solar cells to reduce the reflection coefficient, has been studied.
Materials and methods
The PS samples have been prepared using the original technology described in the paper [15]. The porous layer was generated locally on the monocrystalline silicon substrates with a polished and textured surface by electrochemical etching in an aqueous-alcoholic solution of hydrofluoric acid in the constant current density mode.
The erbium dopant was introduced by impregnating the porous layer with an aqueous solution of Er (NO3) 3 · 5 H2O, followed by annealing in air at the temperature of 950 °C. The initial porous matrix parameters were determined gravimetrically by using the weight loss results after etching and calculating the porous layer volume. The thickness of the sample porous layer was established on the basis of photomicrographs of a sample cross-section, since the optical contrast of the single-crystal substrate region and the porous layer differs significantly (Fig. 1a).
The porosity was calculated by the following formula:
P = = , (1)
where P is the porosity, Δm is a change in the sample mass, S is the porous layer area, d is the thickness of the porous layer, Vpor is the pore volume, Vpor. layer is the volume of the porous layer, ρ is the silicone density (ρ = 2.33 g/cm3). For the samples under study, the porosity ranged from 0.61% to 3.65%. Such low porosity values are explained by the local pore generation process.
The study of the sample microstructure and surface morphology was performed using a TESCAN VEGA electron microscope with a 100,000‑fold magnification in order to control composition of the deposited dopant and to conduct energy-dispersive analysis (Oxford INCAx-act) of the surface of porous silicon samples with the doped erbium impurity.
The Raman spectroscopy of the samples was performed both on the PS surface and on a cross-section of the porous layer at the room temperature. When measuring the Raman spectra, a FOTON-BIO microscope with the laser excitation wavelengths of 532 nm and 785 nm and a 20- and 50‑fold magnification was applied. The laser exposure time varied depending on the signal intensity from 100 ms to 3 000 ms for the samples with various luminescent backgrounds. The spectra were recorded based on the average signal intensity for 3–5 measurements per sample.
The micro-photoluminescence spectra were measured at the room temperature using a BOMEM DA3.36 Fourier spectrometer with a resolution of 1 and 4 cm−1 (0.24 nm and 0.94 nm, respectively). The photoluminescence signal was detected by a cooled germanium detector. An Nd : YAG laser was applied for excitation with the excitation wavelength of 532 nm. In all cases, the laser excitation intensity was 10 mW, the laser beam diameter was equal to ≈10 μm. The measurements were performed in the porous layer region. Since the porous layers were not uniform, the laser beam was focused in such a way as to capture both the etched holes and the areas between them.
Results and discussions
The study of sample surface morphology has showed a non-uniform distribution of erbium deposit clusters on the textured silicon surface. Figure 1b demonstrates a scanning electron microscope (SEM) image of the sample surface in the case of which a porous layer was developed on the textured surface.
Table 1 shows the elemental composition of this sample obtained using a SEM spectral analyzer. The results demonstrate that erbium is located in the porous layer in the clusters that can be determined by the spectra 1, 2 and 3, measured at different points of the structure. Moreover, oxygen is available in the immediate environment of erbium that is a favorable condition for erbium luminescence.
The energy-dispersive analysis of the surface of erbium-doped PS samples has shown various erbium percentages in the samples under study, ranging from 0.88% to 31.6%. For the textured surfaces, there are the areas of heterogeneity, where the deposited layer generates the inclusions of erbium deposits between the tetrahedral pyramids of the silicon surface. It is in these areas that the porous layer is predominantly formed on the textured surface. Therefore, it can be concluded that the erbium ions are predominantly contained in the porous layer.
The energy-dispersive analysis of the sample cleavage has confirmed the results of previously conducted studies [3] that erbium is contained in a noticeable amount (up to 0.1 atm.%) only in the porous layer, its availability is not recorded in the substrate. This indicates the absence of erbium diffusion into the single-crystal silicon at the annealing temperature (950 °C).
Raman spectroscopy
All the analyzed samples have shown the availability of a strong luminescent background both at the wavelength of 532 nm and at the wavelength of 785 nm in the case of laser excitation of the Stokes component of Raman scattering. At the laser excitation wavelength of 532 nm, the spectral lines of erbium oxide and low-dimensional silicon (514 cm−1) (Table 2) were found in the porous silicon samples under study. The crystallite size of porous silicon, according to [16], fluctuates from 2 to 4 nm. In addition to the silicon bond, the low-intensity lines of Si–OH vibrations were found within the spectrum [17]. The available erbium oxide peaks, as well as the shift of the silicon line towards the lower frequencies within the overall spectrum of the samples, measured on a cross section cleavage, confirms the presence of erbium in the porous silicon pores (Fig. 2a). For a more detailed spectral analysis, the peaks of the Raman spectrum obtained at a laser excitation wavelength of 532 nm were analyzed (Fig. 2b). The baseline adjustment and deconvolution analysis allowed us to more accurately determine the sample structure and reveal the availability of anhydrous erbium salt line with a relatively low concentration in comparison to the oxide peaks. The approximation error and the overall deconvolution decomposition error were 1.2%, and the Lorentz function was selected as the function approximating the peaks:
y = y0 + = , (2)
where w is the half-width value at the peak half-height, y0 is the offset equal to the baseline adjustment, yc is the peak center, and A is the peak area.
All peaks of the Er-O bond oscillations can be confirmed by the data provided in the paper [18], where the Raman spectra of monoclinic erbium oxide have been analyzed. The spectra of the Er2O3 B-phase can be divided into four regions: 25 (I) between 70 cm−1 and 125 cm−1, (II) between 150 cm−1 and 220 cm−1, (III) between 240 cm−1 and 300 cm−1, where the lines 2 Ag ≈ 1 Bg typical for the B-phase, are observed; and (IV) between 370 cm−1 and 600 cm−1. The signal at a frequency of 1 062 cm‑1 typical for the oscillation group of the NO3 anion, confirms the availability of low concentration of an anhydrous erbium salt in the sample. Although the erbium nitrate peak within the oscillation range of 1 039–1 062 cm−1 (the NO3 oscillation group [18]) has weak intensity, it is comparable with the weak oscillations of the erbium oxide peaks at the frequencies of 403 and 366 cm−1. The oscillations of nitrogen molecules in N–O bonds and N–H free radicals occur within the Raman spectra even in the presence of high background luminescence [19].
Micro-photoluminescence spectroscopy
Fig. 3 shows the photoluminescence spectra of the prepared samples with a porous layer. In the case of samples No. 1 – No. 6, the pore formation process was performed on a polished surface, in the case of sample No. 8 – on a textured one. All the obtained structures demonstrate rather good luminescent properties at the room temperature without any common concentration quenching of luminescence in such cases. That is, the proposed technology provides for the favorable conditions for luminescence. The spectrum deconvolution has revealed 12 obvious and hidden peaks with a total error of less than 3.3%.
The micro-photoluminescence spectra of absolutely all samples have showed peaks within the wavelength range from 1.46 to 1.58 μm being typical for the erbium multiplets 4I13/2 and 4I15/2, as well as the low-intensity silicon peaks at a wavelength of 1.14 μm.
The samples have a strong difference not only in the intensity of the main erbium photoluminescence peaks, but also demonstrate a clear asymmetry and multiplet energy splitting observed at the room temperature. The sample porosity is the main factor influencing the luminescence intensity. However, not only the layer porosity, but also the internal structure of pores plays an important role. The samples No. 5 and No. 6 have the close porosity values, but the significantly different photoluminescence patterns. The sample No. 5 has demonstrated a weak photoluminescence signal intensity associated with silicon and a fairly strong erbium response compared to other samples. On the contrary, the sample No. 6 has a high silicon response but a weak erbium peak. Such a difference may be due to various pore structures. The strongest luminescence response was demonstrated by the sample No. 8 with a porous layer on a textured surface. Such a strong photoluminescence signal may be due to the minimal radiation leakages when leaving a more ordered textured structure and the availability of additional excitation channels for the erbium impurity ions mediated by the silicon nanocrystals. The sample No. 2 has shown weak erbium luminescence that can be explained by the increase in the silicon oxide layer between the silicon nanocrystals and REM ions [20].
The study of changes in the photoluminescence intensity on the sample surface has shown that it can differ by almost 3 times for various surface regions (Fig.4). For the sample No. 2, the erbium peak is maximum in the area No.1 with the highest porosity. However, in the area No.2, where the porosity is lower, the silicon peak exceeds the erbium one.
Conclusion
The study results demonstrate that the structure of initial porous matrix has a significant impact on the luminescent properties of the subsequent structures generated with the oxidized PS layers doped with erbium. The main factor affecting the luminescence intensity is the sample porosity. The erbium nitrate precipitate is concentrated to the greater extent in the porous region, while after annealing mainly the erbium oxide compounds are generated. Moreover, the available oxygen in the immediate environment of erbium develops favorable conditions for luminescence.
The geometrical arrangement and internal structure of the pores play an important role in this case. The most intense photoluminescent response has been observed in the sample with a porous layer generated on a textured surface, for which the conditions of minimal radiation leakages are implemented when abandoning the ordered structure. A decrease in the luminescence intensity in some samples with the sufficiently high porosity may be due to an increase in the silicon oxide layer between the silicon nanocrystals and erbium ions that, as a consequence, should lead to a decrease in the excitation efficiency of the rare-earth metal ions.
The established relations between the luminescent properties and structure of samples with the oxidized porous silicon doped with erbium can be useful for developing the production technology for the highly efficient IR LEDs on a silicon substrate operating at the room temperature.
AUTHORS
D. N. Artemiev. ORCID: 0000-0002-1942-8205
N. V. Latukhina. ORCID: 0000-0003-2651-0562
A. A. Melnikov. ORCID: 0000-0003-2651-0562
M. V. Stepikhova. ORCID: 0000-0001-8269-0348
D. N. Artemiev1, N. V. Latukhina1, A. A. Melnikov1,
D. A. Nesterov1, M. V. Stepikhova2, E. Kh. Khamzin1
Korolev Samara National Research University, Samara, Russia
Instituteof Physics of Microstructures of the Russian Academy of Sciences, Nizhny Novgorod, Russia
This paper is devoted to the study ofluminescent properties of porous silicon doped with erbium. The development of semiconductor materials activated by the lanthanides is a vital task of contemporary physics and technology of optoelectronic devices. The object of research is oxidized porous silicon doped with the erbium ions. The structural and morphological analysis and study of the luminescent properties of luminescent structure samples based on the porous silicon doped with erbium have been performed. The studies have been carried out by the methods of scanning electron microscopy, Raman spectroscopy and micro-photoluminescence spectroscopy. The analysis of samples has demonstrated a correlation between the process parameters of the produced luminescent structures and efficiency of their photoluminescence. The results of studies can be used as a basis for the production method of silicon luminescent structures for optoelectronics.
Key words: porous silicon, rare earth elements, erbium, scanning electron microscopy, micro-photoluminescence, Raman spectroscopy.
Article received:07.06.2024
Article accepted: 29.10.2024
Introduction
Porous silicon (PS) doped with erbium attracts attention as a material on the basis of which an efficient IR LED on a silicon substrate operating at the room temperature can be obtained. The development of such a device will allow a transition to the completely silicon optoelectronics that will significantly increase the capacity of all data processing systems, their speed, interference immunity and other parameters. PS, as a system of nanocrystals, provides an efficient mechanism to transfer the pumping energy to the luminescent centers connected with the erbium ions [1, 2]. The nanocrystalline silicon systems with erbium are of particular interest since the Er3+ ionprovides a narrow temperature-independent spectral response at a wavelength of 1.55 μm that corresponds to the spectral window of quartz light guides [3, 4]. In addition, in the systems with erbium ions, the up-conversion phenomenon is observed that allows converting the near-IR radiation into the visible light. It can be used to develop the up-conversion coatings for efficient silicon solar cells [5–7]. In [8], it has been shown that the intense optical pumping of silicon nanocrystals can lead to the inverse population of Er3+ ion states, resulting in the necessary condition for optical amplification in these structures. In this regard, the studies of PS luminescent systems with erbium are of great interest. It has been shown that the luminescence efficiency in PS can be changed by introduction of certain impurities [9–11] or by special material treatment to prevent erbium clustering [12, 13]. The studies with the scanning electron microscopy and Raman spectroscopy methods have also made it possible to determine a clear dependence of the luminescent properties of porous silicon on the dimensions of PS nanocrystals [14]. This indicates the crucial role of the structure and composition of the erbium ion immediate environment in the luminescence signal generation. Thus, the review of conducted studies demonstrates the importance of structural and morphological analysis of luminescent systems with porous silicon and identification of the most important parameters efficient for the luminescence excitation mechanisms. In this paper, the erbium distribution in the porous silicon samples with a textured surface that is conventionally used in the silicon solar cells to reduce the reflection coefficient, has been studied.
Materials and methods
The PS samples have been prepared using the original technology described in the paper [15]. The porous layer was generated locally on the monocrystalline silicon substrates with a polished and textured surface by electrochemical etching in an aqueous-alcoholic solution of hydrofluoric acid in the constant current density mode.
The erbium dopant was introduced by impregnating the porous layer with an aqueous solution of Er (NO3) 3 · 5 H2O, followed by annealing in air at the temperature of 950 °C. The initial porous matrix parameters were determined gravimetrically by using the weight loss results after etching and calculating the porous layer volume. The thickness of the sample porous layer was established on the basis of photomicrographs of a sample cross-section, since the optical contrast of the single-crystal substrate region and the porous layer differs significantly (Fig. 1a).
The porosity was calculated by the following formula:
P = = , (1)
where P is the porosity, Δm is a change in the sample mass, S is the porous layer area, d is the thickness of the porous layer, Vpor is the pore volume, Vpor. layer is the volume of the porous layer, ρ is the silicone density (ρ = 2.33 g/cm3). For the samples under study, the porosity ranged from 0.61% to 3.65%. Such low porosity values are explained by the local pore generation process.
The study of the sample microstructure and surface morphology was performed using a TESCAN VEGA electron microscope with a 100,000‑fold magnification in order to control composition of the deposited dopant and to conduct energy-dispersive analysis (Oxford INCAx-act) of the surface of porous silicon samples with the doped erbium impurity.
The Raman spectroscopy of the samples was performed both on the PS surface and on a cross-section of the porous layer at the room temperature. When measuring the Raman spectra, a FOTON-BIO microscope with the laser excitation wavelengths of 532 nm and 785 nm and a 20- and 50‑fold magnification was applied. The laser exposure time varied depending on the signal intensity from 100 ms to 3 000 ms for the samples with various luminescent backgrounds. The spectra were recorded based on the average signal intensity for 3–5 measurements per sample.
The micro-photoluminescence spectra were measured at the room temperature using a BOMEM DA3.36 Fourier spectrometer with a resolution of 1 and 4 cm−1 (0.24 nm and 0.94 nm, respectively). The photoluminescence signal was detected by a cooled germanium detector. An Nd : YAG laser was applied for excitation with the excitation wavelength of 532 nm. In all cases, the laser excitation intensity was 10 mW, the laser beam diameter was equal to ≈10 μm. The measurements were performed in the porous layer region. Since the porous layers were not uniform, the laser beam was focused in such a way as to capture both the etched holes and the areas between them.
Results and discussions
The study of sample surface morphology has showed a non-uniform distribution of erbium deposit clusters on the textured silicon surface. Figure 1b demonstrates a scanning electron microscope (SEM) image of the sample surface in the case of which a porous layer was developed on the textured surface.
Table 1 shows the elemental composition of this sample obtained using a SEM spectral analyzer. The results demonstrate that erbium is located in the porous layer in the clusters that can be determined by the spectra 1, 2 and 3, measured at different points of the structure. Moreover, oxygen is available in the immediate environment of erbium that is a favorable condition for erbium luminescence.
The energy-dispersive analysis of the surface of erbium-doped PS samples has shown various erbium percentages in the samples under study, ranging from 0.88% to 31.6%. For the textured surfaces, there are the areas of heterogeneity, where the deposited layer generates the inclusions of erbium deposits between the tetrahedral pyramids of the silicon surface. It is in these areas that the porous layer is predominantly formed on the textured surface. Therefore, it can be concluded that the erbium ions are predominantly contained in the porous layer.
The energy-dispersive analysis of the sample cleavage has confirmed the results of previously conducted studies [3] that erbium is contained in a noticeable amount (up to 0.1 atm.%) only in the porous layer, its availability is not recorded in the substrate. This indicates the absence of erbium diffusion into the single-crystal silicon at the annealing temperature (950 °C).
Raman spectroscopy
All the analyzed samples have shown the availability of a strong luminescent background both at the wavelength of 532 nm and at the wavelength of 785 nm in the case of laser excitation of the Stokes component of Raman scattering. At the laser excitation wavelength of 532 nm, the spectral lines of erbium oxide and low-dimensional silicon (514 cm−1) (Table 2) were found in the porous silicon samples under study. The crystallite size of porous silicon, according to [16], fluctuates from 2 to 4 nm. In addition to the silicon bond, the low-intensity lines of Si–OH vibrations were found within the spectrum [17]. The available erbium oxide peaks, as well as the shift of the silicon line towards the lower frequencies within the overall spectrum of the samples, measured on a cross section cleavage, confirms the presence of erbium in the porous silicon pores (Fig. 2a). For a more detailed spectral analysis, the peaks of the Raman spectrum obtained at a laser excitation wavelength of 532 nm were analyzed (Fig. 2b). The baseline adjustment and deconvolution analysis allowed us to more accurately determine the sample structure and reveal the availability of anhydrous erbium salt line with a relatively low concentration in comparison to the oxide peaks. The approximation error and the overall deconvolution decomposition error were 1.2%, and the Lorentz function was selected as the function approximating the peaks:
y = y0 + = , (2)
where w is the half-width value at the peak half-height, y0 is the offset equal to the baseline adjustment, yc is the peak center, and A is the peak area.
All peaks of the Er-O bond oscillations can be confirmed by the data provided in the paper [18], where the Raman spectra of monoclinic erbium oxide have been analyzed. The spectra of the Er2O3 B-phase can be divided into four regions: 25 (I) between 70 cm−1 and 125 cm−1, (II) between 150 cm−1 and 220 cm−1, (III) between 240 cm−1 and 300 cm−1, where the lines 2 Ag ≈ 1 Bg typical for the B-phase, are observed; and (IV) between 370 cm−1 and 600 cm−1. The signal at a frequency of 1 062 cm‑1 typical for the oscillation group of the NO3 anion, confirms the availability of low concentration of an anhydrous erbium salt in the sample. Although the erbium nitrate peak within the oscillation range of 1 039–1 062 cm−1 (the NO3 oscillation group [18]) has weak intensity, it is comparable with the weak oscillations of the erbium oxide peaks at the frequencies of 403 and 366 cm−1. The oscillations of nitrogen molecules in N–O bonds and N–H free radicals occur within the Raman spectra even in the presence of high background luminescence [19].
Micro-photoluminescence spectroscopy
Fig. 3 shows the photoluminescence spectra of the prepared samples with a porous layer. In the case of samples No. 1 – No. 6, the pore formation process was performed on a polished surface, in the case of sample No. 8 – on a textured one. All the obtained structures demonstrate rather good luminescent properties at the room temperature without any common concentration quenching of luminescence in such cases. That is, the proposed technology provides for the favorable conditions for luminescence. The spectrum deconvolution has revealed 12 obvious and hidden peaks with a total error of less than 3.3%.
The micro-photoluminescence spectra of absolutely all samples have showed peaks within the wavelength range from 1.46 to 1.58 μm being typical for the erbium multiplets 4I13/2 and 4I15/2, as well as the low-intensity silicon peaks at a wavelength of 1.14 μm.
The samples have a strong difference not only in the intensity of the main erbium photoluminescence peaks, but also demonstrate a clear asymmetry and multiplet energy splitting observed at the room temperature. The sample porosity is the main factor influencing the luminescence intensity. However, not only the layer porosity, but also the internal structure of pores plays an important role. The samples No. 5 and No. 6 have the close porosity values, but the significantly different photoluminescence patterns. The sample No. 5 has demonstrated a weak photoluminescence signal intensity associated with silicon and a fairly strong erbium response compared to other samples. On the contrary, the sample No. 6 has a high silicon response but a weak erbium peak. Such a difference may be due to various pore structures. The strongest luminescence response was demonstrated by the sample No. 8 with a porous layer on a textured surface. Such a strong photoluminescence signal may be due to the minimal radiation leakages when leaving a more ordered textured structure and the availability of additional excitation channels for the erbium impurity ions mediated by the silicon nanocrystals. The sample No. 2 has shown weak erbium luminescence that can be explained by the increase in the silicon oxide layer between the silicon nanocrystals and REM ions [20].
The study of changes in the photoluminescence intensity on the sample surface has shown that it can differ by almost 3 times for various surface regions (Fig.4). For the sample No. 2, the erbium peak is maximum in the area No.1 with the highest porosity. However, in the area No.2, where the porosity is lower, the silicon peak exceeds the erbium one.
Conclusion
The study results demonstrate that the structure of initial porous matrix has a significant impact on the luminescent properties of the subsequent structures generated with the oxidized PS layers doped with erbium. The main factor affecting the luminescence intensity is the sample porosity. The erbium nitrate precipitate is concentrated to the greater extent in the porous region, while after annealing mainly the erbium oxide compounds are generated. Moreover, the available oxygen in the immediate environment of erbium develops favorable conditions for luminescence.
The geometrical arrangement and internal structure of the pores play an important role in this case. The most intense photoluminescent response has been observed in the sample with a porous layer generated on a textured surface, for which the conditions of minimal radiation leakages are implemented when abandoning the ordered structure. A decrease in the luminescence intensity in some samples with the sufficiently high porosity may be due to an increase in the silicon oxide layer between the silicon nanocrystals and erbium ions that, as a consequence, should lead to a decrease in the excitation efficiency of the rare-earth metal ions.
The established relations between the luminescent properties and structure of samples with the oxidized porous silicon doped with erbium can be useful for developing the production technology for the highly efficient IR LEDs on a silicon substrate operating at the room temperature.
AUTHORS
D. N. Artemiev. ORCID: 0000-0002-1942-8205
N. V. Latukhina. ORCID: 0000-0003-2651-0562
A. A. Melnikov. ORCID: 0000-0003-2651-0562
M. V. Stepikhova. ORCID: 0000-0001-8269-0348
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