未掺杂半绝缘砷化镓中EL2能级的光电离截面谱

SPECTRAL DISTRIBUTION OF PHOTO-IONIZATION CROSS SECTIONS FOR EL2 LEVEL IN UNDOPED SEMI-INSULATING GaAs

采用恒流光电导方法,在不同温度下测量了未掺杂半绝缘LEC砷化镓中EL2能级的光电离截面谱σ_n^0-hv。发现截面谱中有三个上升较快的台阶,认为它们来源于EL2能级上的电子向导带上三个极点Γ、L、X的光跃迁。σ_n^0-hv的理论计算和实验曲线符合得很好,并得出有关EL2能级的物理量即束缚能E_T、Frank-Condon移动d_(FC)和波函数扩展长度α^(-1)。

The spectral distribution of photo-ionization cross sections σ_n^0-hv for the EL2 level in undoped LEC semi-insulating GaAs is measured at different temperature using constant current photoconductivity. Three steps have been clearly found in the spectra. The spectral shape of all σ_n^0(hv) curves appears to be related to the electron transitions from EL2 level to T, L, X, minima of the conduction band. The theoretical calculation agrees well with the experimental data, moreover, the physical parameters of EL2 level, such as binding energy E_T, Frank-Condon shift d_(FC) and extension length of wave function α^(-1), have been obtained.