ELECTRON INTERVALLEY SCATTERING IN GALLIUM-ARSENIDE

The authors briefly review the experimental and theoretical studies of electron intervalley transfer in gallium arsenide. The review includes the data obtained by time-resolved optical measurements, high-field transport studies, quasiballistic transport investigations, etc, and contains information about electron intervalley scattering intensity. Despite the occurrence of a number of recent studies devoted to electron intervalley transfer in gallium arsenide the problem concerning the intensity of the Gamma -L intervalley scattering is shown to be still answered. It is shown that the different experiments and their interpretations yield quite different values of the Gamma -L intervalley coupling constant DGamma L which varies in the range (1.5-10)*108 eV cm-1. They have tried to understand these contradictory results in terms of electron trapping at resonant impurity states and in terms of non-conventional scattering mechanisms, which are important at high excitation levels and energies. The role of hot phonons and electron intervalley Gamma -X and L-X scattering in the electron relaxation and intervalley transfer is analysed and discussed. It is demonstrated that inclusion of hot phonons and the X valleys allows the explanation of some contradictory experimental results in the framework of one intervalley scattering model.