Low-energy-electron-loss spectroscopy of thin Ge layers on a GaAs(100) surface

Abstract

The interdiffusion behavior at the Ge/GaAs(100) interface has been studied by low-energy- electron-loss spectroscopy (LEELS) and Auger electron spectroscopy (AES). Ge was deposited on the cleaned GaAs(100)-4x6 surface maintained at 320 and 450 ° C up to 14 and 16 Å, respectively. The decrease of the AES signals due to Ga (55 eV) and As (32 eV) with Ge deposition reveals that the interdiffusion does not occur significantly for 320 ° C deposition, and it proceeds faster between As and Ge than between Ga and Ge when the interdiffusion occurs at higher temperature. In LEELS measurements for 450 ° C deposition, a new peak appears at 20.1 eV due to a transition between Ga3d levels of Ga which has diffused out into the Ge film on the GaAs and the conduction band of Ge. With subsequent annealing at higher temperature, the interdiffusion occurs at the surface, and the surface electronic structure finally becomes almost the same as that of GaAs.