摘要
用３个特征频率的爱因斯坦模型，以Ｇｒｕｎｅｉｓｅｎ参数γｉ和约化的电子一声子耦合强度（ｇ２Ｆ）ωｉ为参数，较好地拟合了Ｇｅ和ＧａＡｓ的线膨胀系数与能隙的温度关系的实验曲线，结果表明ＴＡ声子的负的Ｇｒｕｎｅｉｓｅｎ参数是引起低温区Ｇｅ和ＧａＡｓ的线膨胀系数反常的原因，同时，Ｇｅ和ＧａＡｓ的价带顶状态的（ｇ２Ｆ）ωｉ为正值，而导带底状态的相应量为负值．
Temperature dependence of the thermal expansion and that of the energy band gap for Ge and GaAs are investigated using the Einstein phonon model with three characteristic frequencies ωi,i= 1, 2, 3. Using the Gruneisen constants γi and the electron-phonon coupling spectral function (g2F)i as the adjusting parameters, the observed temperature dependence of the thermal expansion coefficient α(T) and that of the band gap Eg(T) are reproduced. The result shows that the negative γ of TA mode may be responsible for the negative α in low temperature region for these materials.The negative and positive values of el-ph coupling spectral function respectively for the bottom of the conduction band and the top of the valence band in Ge and GaAs are shown.
出处
《红外与毫米波学报》
SCIE
EI
CAS
CSCD
北大核心
1994年第3期173-180,共8页
Journal of Infrared and Millimeter Waves
关键词
锗
砷化镓
能隙
Einstein model, linear expansion coefficient, Ge, GaAs, TA phonon.
