Monte Carlo calculation of hot electron mobility in PbS

Electron mobilities in PbS at a lattice temperature of 77°K have been calculated by the Monte Carlo method. The effects of the band nonparabolicity and of the deformation potential acoustic and polar optical phonon scattering have been included in the calculations. The results are compared with experiments and with the ones obtained on the basis of a displaced Maxwellian distribution function.     

Hot electron drift velocity in Hg1−xCdxTe (x=0.205)

Hot electron drift velocity in Hg_1?xCd_xTe (x=0.205) at 77 K is calculated by the Monte Carlo technique. Band nonparabolicity, admixture of wave functions, and two-mode nature of the polar optic phonons are included in addition to the effects of deformation potential acoustic, alloy and ionized impurity scattering. Good agreement with the experimental data is achieved.     

PID自动控温仪在变温霍耳效应研究中的应用简

应用计算机控制的PID控温仪研究了锑化铟样品的变温霍耳效应。通过在线控制并记录77K～300K温度范围内锑化铟样品的霍耳电压，估测了样品的禁带宽度。     

Low-temperature hot-electron energy relaxation in Hg0.8Cd0.2Te in extreme-quantum-limit magnetic fields

Energy relaxation time of hot electrons in Hg_0.8Cd_0.2Te at a lattice temperature of 1.5 K is calculated for quantizing magnetic flux densities of 4 and 6 T considering acoustic scattering via deformation potential and piezoelectric couplings. Band nonparabolicity, nonequipartition of phonons, screening of the scattering rates due to carrier space charge, and low-temperature broadening of the Landau level are incorporated. The calculated results agree qualitatively with experimental data.     

Hot-Electron Magneto-Transport in InSb

The balance equations are used to investigate the hot electron magneto-transport in narrowgap semiconductor InSb at 77 K in crossed weak magnetic field and electric field. In the case of vanishing transverse velocity, the drift mobility and the Hall mobility are calculated and it is shown that the Hall factor in InSb at 77K is less than 1 and decreases with electric field. In the case of vanishing transverse electric field, the longitudinal velocity and the transverse velocity are calculated as a function of the magnetic field and the electric field. The effect of the magnetic field on the longitudinal velocity is different from that on the transverse velocity.     

Calculation on hot-electron noise in semiconductors

Under hot-electron conditions, noise arises both from fluctuations in the carrier velocity and the carrier collision time. The magnitudes of these two contributions are calculated by the Monte-Carlo method for InSb at 77°K.     

Screening effects on polar mode scattering at high electric fields

The effects of screening of polar optical mode of scattering at high electric fields are studied by performing Monte Carlo calculations on InSb at 77 K. The average carrier energy is found to be markedly affected by the inclusion of screening.     

Scattering mechanisms in p-type GaSb in the temperature range 30–300°K

In a former paper[1], we have shown that the magnetoresistance coefficient in p-type GaSb (1+ξ) remains close to 1 at 77°K and that the mobilities ratio remains equal to 6 in the temperature range 77–300°K.We show from these results that between 30 and 300°K, the predominant scattering is a mixed scattering by lattice vibrations and ionized impurities. Interband scattering is the predominant process for light holes, while heavy holes undergo intraband scattering. In this temperature range, this mechanism accounts for the mobility variation, a result which had not been found so far on p-type GaSb.     

Galvanomagnetic effects in n-type gallium antimonide

This paper reports the theoretical and experimental study performed on Hall mobility and free carrier Faraday rotation in a degenerate n-GaSb sample in the temperature range 77–300K. Following relaxation time approximation the mobility is estimated separately for the Γ- and L-valley taking into account the scattering of electrons due to ionised impurities, space charge, polar optical phonons, deformation potential, intervalley acoustic and optical phonons. The effective mobility is calculated considering a two valley model, degeneracy and non-parabolicity of the Γ-valley, and compared with these experimental results. Microwave Faraday rotation data at 77 and 300K is analysed generalising the d.c. magneto-conductivity tensor components as derived by Bordure and Savelli to the high frequency, and is used to confirm the scattering mechanisms and band parameters used in the analysis of d.c. galvanomagnetic results.     

The effect of high magnetic fields on degenerate band excitons in InSb

A variational technique is used to calculated the binding energy of degenerate band excitons in InSb as a function of magnetic field. the nonparabolicity of the conduction bands is taken into account and standard perturbation theory is used for deviation of the valence bands from the spherical. A comparison of the theoretical results and available experimental results is made.     

Electron spin lifetimes in Hg0.78Cd0.22 Te and InSb

We have made direct pump–probe measurements of spin lifetimes in long wavelength narrow-gap semiconductors at wavelengths between 4 and 10 μm and from 4 to 300 K. In particular, we measure remarkably long spin lifetimes, τ_s300 ps, even at 300 K for epilayers of degenerate n-type InSb. In this material the mobility is approximately constant between 77 and 300 K, and we find that τ_s is approximately constant in this temperature range. In order to determine the dominant spin relaxation mechanism we have investigated the temperature dependence of τ_s in non-degenerate lightly n-type Hg_0.78Cd_0.22Te of approximately the same band gap as InSb, and find that τ_s varies from 356 ps at 150 K to 24 ps at 300 K. Our results, both in magnitude and temperature dependence of τ_s, imply that the Elliott–Yafet model dominates in these materials.     

Determination of the energy relaxation time in GaSb from microwave harmonic mixing and transport phenomena

The energy relaxation time τ_? of GaSb has been determined independently from microwave harmonic mixing experiments in the range of 160–200 K and from the current-voltage characteristics at 300 and 77 K. From measurements of the i.r. Faraday effect at 300 K valley populations as a function of the electric field strength are obtained which are in agreement with values calculated with help of the energy relaxation time obtained by methods mentioned before. For the evaluation of the data a two-band model has been used. The results obtained from the microwave experiments are extrapolated to 300 and 77 K assuming polar optical mode scattering. Good agreement of these values and the results obtained from the current-voltage characteristics and the Faraday measurements was found. The values for 300 and 77 K are 4 × 10⁻¹² sec and approximately 1·6 × 10⁻¹¹ sec, respectively.     

On the problem of magnetic freeze-out in indium antimonide

The reduction of the free electron concentration in pure n-type InSb as a function of a strong magnetic field was calculated based on a model of a single hydrogen-like impurity. The nonparabolicity, the g-factor and the excited impurity states were taken into account, the influence of temperature and various degrees of compensation are discussed.     

Negative differential mobility in PbTe and PbSnTe at high electric fields

Monte Carlo calculations of hot-electron drift velocity in PbTe and Pb_0.8Sn_0.2Te at 77 K are reported. The relevant scattering mechanisms together with band-structure nonparabolicity and anisotropy are included in the calculations. A negative differential mobility (NDM) does not appear when the electrons are assumed to remain confined within the L valleys of the conduction band. On the contrary, allowing for electron transfer into the W valleys and taking suitable values of the parameters related to these valleys, an NDM appears and the threshold field for the same agrees well with the experimental data. Alloy scattering in PbSnTe is found to reduce the NDM.     

Warped band and anisotropy of the hot-hole drift velocity in Si between 300 and 430 K

Experimental evidence of the anisotropy in the hot-hole drift velocity v_d of Si between 300 and 430°K has been theoretically proved to be strongly correlated to the warped shape of the heavy valence band. The comparison between theory and experiments permits a valuable check on the competitive role played by the strong nonparabolicity of the Si valence band and the lattice scattering mechanisms.     

Shubnikov-de Haas effect and effective mass inn-InP in dependence on carrier concentration

Shubnikov-de Haas investigations onn-InP are presented and the effective mass as a function of carrier concentration is determined. The experiments are carried out with bulk and liquid phase epitactically grown material and carrier concentrations betweenn=10¹⁷ and 10¹⁹cm^–3. Temperatures employed ranged fromT=2 to 77 K and magnetic fields were applied up toB=22 T. Supplementing Kane's theory by introducing both temperature and electron concentration dependence, the nonparabolicity of the effective mass for temperatures betweenT=0 K and 300 K is calculated. The result fits quite well to the experimental results.Dedicated to Prof. Dr. Günter Lautz on the occasion of his 70th birthday     

On frequency multiplication in the millimeter range inn-InSb

An experimental investigation was made of the generation of the third harmonic in n-InSb at a temperature 77K in the millimeter range of wavelengths. The results are compared with a theoretical calculation on the assumption that the nonlinear susceptibility is caused by the nonparabolicity of the conduction bands.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 15, No. 2, pp. 300–304, February, 1972.In conclusion the authors sincerely thank A. M. Belantsev and V. N. Genkin for discussing the results of the work and for a number of valuable comments.     

Enhanced optical nonlinearities of superlattices within the Kronig-Penney model incorporating inherent bulk nonlinearities

Third order nonlinear optical susceptibilities χ⁽³⁾ of GaAs/Ga_1?xAlAs superlattices have been predicted which are two orders of magnitude larger than those of bulk GaAs. This enhancement is due to the band nonparabolicity arising from the additional periodicity of the superlattice. These predictions, based on a tight-binding model of the superlattice dispersion, are here extended to the more realistic Kronig-Penney (KP) model. Corrections to tight-binding are non-negligible; however, enhancements of χ⁽³⁾ are still large but reduced approximately 30%–50% over previous estimates. The KP model is also here applied to superlattices employing InSb as the quantum well material. Because of the smaller effective mass of InSb, and taking account of its bulk nonparabolicity, the minibands move to higher energy, enhancing the interwell overlap and increasing χ⁽³⁾ by about one order of magnitude over that of bulk InSb. The role of the barrier material in this case is important and is discussed. The interplay between the bulk nonparabolicity and that arising from the superlattice is also addressed.     

Effects of non-equilibrium polar optic phonons and the band non-parabolicity on small signal high-frequency hot electrons ac mobility in narrow gap semiconductors in high magnetic fields

The small signal high-frequency ac mobility of hot electrons in n-HgCdTe in the extreme quantum limit at low and high temperatures have been calculated considering the non-equilibrium phonon distribution as well as the thermal phonon distribution .The energy loss rate has been calculated considering only optical phonon scattering while the momentum loss rate has been calculated considering acoustic phonon scattering and piezoelectric scattering together with polar optical phonon scattering and separately considering only the polar optical scattering. The results have been discussed and compared. It has been observed that at 20 K, the normalized mobility considering all the three scattering mechanisms differs appreciably from that considering only the polar optical phonon scattering. However, at 77 K, there is no difference in the normalized mobility. This establishes the fact that at higher temperature, the effect of acoustic phonon scattering and piezoelectric coupling is negligible, compared to the polar optical phonon scattering. So the ac mobility considering only polar optical phonon scattering has been studied at 77 and 20 K. The ac mobility is found to remain constant up to 100 GHz and thereafter it started decreasing at higher frequencies at 77 K whereas the ac mobility reduces at much lower frequencies at lower temperature at lower field. The non-parabolicity of the band structure enhances the normalized mobility.     

液氮冲击中锑化铟焦平面探测器形变研究

液氮冲击中锑化铟红外焦平面探测器(InSb IRFPAs)的形变研究对理解探测器结构设计可靠性、预测探测器耐冲击寿命具有重要意义.在系统分析液氮冲击结束时模拟得到的InSb IRFPAs形变分布与方向的基础上,提出了降温过程中累积热应变完全弛豫的设想,升至室温后的模拟结果重现了室温下拍摄的InSb IRFPAs典型形变分布特征.经分析认为室温下拍摄的InSb IRFPAs表面屈曲变形源于底充胶固化中引入的残余应力应变,变形幅度随降温过程逐步减弱,至77 K时完全消失,升温过程则依据弹性变形规律复现典型棋盘格屈曲模式.这为后续InSb IRFPAs结构设计、优化及耐冲击寿命预测提供了理论分析基础.