High Hole Mobility Polycrystalline GaSb Thin Films

The cost of thermophotovoltaic converters can be reduced by making substrates of amorphous materials, which do not have an orienting effect, such as glass or fused quartz, for obtaining thin polycrystalline GaSb layers. The study establishes the conditions for the crystallization of thin polycrystalline GaSb layers with grain size sufficient to produce efficient thermophotovoltaic converter structures on a non-orienting substrate made of fused quartz. The authors carry out a two-dimensional modeling of the initial nucleus growth to study how the crystallization conditions affect the shape of the grains. It is shown that the form of grain growth is not very sensitive to the initial nucleus size and cooling rate, but is rather sensitive to nucleus density on the surface. The paper provides an estimate of the average surface density of the new phase nuclei, which tend to grow, on substrate surfaces. When the temperature is increased, the surface concentration of nuclei grows, and the grain size decreases. It is determined that the selected range of grain surface density corresponds to the cultivation temperature range of 450—550°С. Thin polycrystalline GaSb layers are grown at 520°С with a cooling rate of 10°C/ min to a temperature of 400°C, using a method developed by us, which requires simple equipment and consists in the forced cooling of a thin layer of stibium in a gallium melt in a vacuum. The degree of crystallinity of the samples is estimated from the photoluminescence spectra at 77 K. The spectra show two emission bands: one at 796 meV and another, the predominant one, at 775 meV, which indicates the presence of a significant number of point defects and deviations from the stoichiometry of the obtained films. The studies performed on an interference microscope show that the obtained layers have good planarity and homogeneity, and the average grain size is up to 25 microns, which confirms the validity of the proposed models. This technology can be used to manufacture inexpensive infrared radiation converters and, in particular, thermophotovoltaic converters.

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Crystallization processes of thin polycrystalline layers of galium stybnide for thermophotovoltaic application

Bahanov

Shutov

Tsybulenko

et al. 2022

ТКЭА

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Correct determination of electron concentration in n–GaSb from Hall data

Parkhomenko

Белов

Молодцова

et al. 2023

Izv. vysš. učebn. zaved., Mater. èlektron. teh.

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The calculation of conductivity electron concentrations in n-GaSb at T = 295 K and T = 77 K have been made. The concentration of “heavy” electrons in the L-valley of conduction band at Т = 295 K has been shown to exceed “light” electron one in the Γ-valley. On the contrary, at T = 77 K the conductivity electrons are gathered in the Γ-valley.The results of Hall measurements made on tellurium-doped samples of n-GaSb obtained by the Czochralski method have been represented. It has been shown that upon analysing Hall data at Т = 295 K, it is necessary to take into account the presence of two types of electrons (“light” and “heavy”); their concentrations are not possible to be determined. Seeming increase in electron concentration upon transition from T = 295 K to 77 K really does not take place. The electron concentration at T = 77 K may be determined correctly from the Hall data.

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Correct determination of electron concentration in n-GaSb by electrical measurements

Parkhomenko¹,

Белов²,

Молодцова³

et al. 2022

MoEM

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The concentrations of conduction electrons in n-GaSb at 295 and 77 K have been calculated taking into account the non-parabolic deviation of the conduction band shape. We show that at T = 295 K the concentration of heavy electrons in the L-valley of the conduction band is higher than the concentration of light electrons in the Г-valley. On the contrary, at T = 77 K the conduction electrons are mostly concentrated in the Г-valley. Hall data for tellurium doped CZ n-GaSb specimens have been reported. Analysis of experimental data for T = 295 K requires the existence of two types of electrons be taken into account (the light and the heavy ones), the concentrations of which cannot be determined. The apparent increase in the electron concentration with a decrease in the temperature from 295 to 77 K is not true. The concentration of conduction electrons at T = 77 K can be measured correctly with the Hall method.

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High Hole Mobility Polycrystalline GaSb Thin Films

Cited by 3 publications

References 39 publications

Crystallization processes of thin polycrystalline layers of galium stybnide for thermophotovoltaic application

Crystallization processes of thin polycrystalline layers of galium stybnide for thermophotovoltaic application

Correct determination of electron concentration in n–GaSb from Hall data

Correct determination of electron concentration in n-GaSb by electrical measurements

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