This paper gives a description of an experimental determination of distribution functions in k→ space of hot holes in uniaxially compressed germanium. The hot-carrier studies were made at 85°K at fields up to 1000 V/cm and uniaxial stresses up to 11 800 kg/cm2. The field and stress were always in the 〈111〉 direction. For the highest stresses, the maximum fields were close to the threshold for current oscillations. The distribution functions were obtained from experimental modulation of intervalence-band absorption of infrared radiation. In order to interpret the results, a parametrized distribution function has been assumed. The parameters of the distribution function are then fitted to the experimental modulation. The calculation of absorption was performed numerically, using a four-band k→·p→ model. This model was checked for consistency by comparing with piezoabsorption measurements performed in thermal equilibrium. The average carrier energy calculated from the distribution function shows a fast increase with stress and almost saturates when the strain splitting of the two p3 / 2 levels reaches the optical-phonon energy. This saturation is interpreted in terms of the change in scattering probabilities with stress. A model based on the nonparabolicity of the upper p3 / 2 level is proposed for the negative differential conductivity in stressed p-type Ge.
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机译:本文描述了单轴压缩锗中热孔k→空间中分布函数的实验确定。热载流子研究是在85°K的条件下进行的,电场最高为1000 V / cm,单轴应力最高为11800 kg / cm2。场和应力始终沿<111>方向。对于最高应力,最大磁场接近电流振荡的阈值。分布函数从红外辐射的间隔带吸收的实验调制获得。为了解释结果,已假定参数化分布函数。然后将分布函数的参数拟合到实验调制中。使用四频带k→·p→模型对吸收率进行数值计算。通过与在热平衡下进行的压电吸收测量值进行比较,检查了该模型的一致性。由分布函数计算出的平均载流子能量随应力迅速增加,并且当两个p3 / 2能级的应变分裂达到光声子能量时几乎饱和。该饱和度是根据散射概率随应力的变化来解释的。针对应力p型Ge的负差电导率,提出了基于上p3 / 2水平的非抛物线性的模型。
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