Energy distributions and emission coefficients of secondary ions ejected from AIIIBV group semiconductors

Abstract

The energy distributions of Ga+ and Ga2+ secondary ions sputtered from the surface of single crystals of GaAs and GaP by Ar+ (E = 18 keV, j = 1·10−6 A/cm2) ions were studied. Integral emission coefficients for secondary ions from four semiconductors (GaAs, GaP, InAs, and A10.35Ga0.65As) bombarded by Ar+ ions (E = 2 keV, j0 = 1·10−6 A/cm2) were also measured. It is shown that the energy distribution of the Ga+ secondary ions are broad and qualitatively similar to distributions of secondary ions sputtered from metal oxide surfaces. Very high integral emission coefficients (up to 20–30%) for secondary ions are also observed, exceeding analogous coefficients for clean metal surfaces. These facts (the significant number of low energy secondary electrons and high secondary ion emission coefficients) are due to the lower density of free electrons in comparison with metals, which ensures a high degree of survival of sputtered ions, and the partially ionic character of the bonds in the semiconductors under study.