Ion beam etching induced structural and electronic modification of InAs and InSb surfaces studied by Raman spectroscopy

The modification of the structural and electronic properties of InAs and InSb surfaces induced by low-energy N-2 and Ar ion beam etching (IBE) were investigated as a function ion energy (less than or equal to 500 eV) using Raman spectroscopy. A drastic enhancement of the electron concentration in the near surface region of both materials independent of the ion energy and the process gas was observed. From Raman measurements in different polarization configurations it can be concluded that the electron accumulation observed after IBE is inherently related to the process-induced structural defects. The degree of structural damage and the carrier concentration in the near surface region increase for higher ion energies. By controlled, subsequent removal of the damaged surface layer using wet etching, the depth profile of the structural and electronic damage in InAs was determined. This procedure reveals that the structural and electronic damage extends about 100 nm into the material. Nevertheless, it can be recognized that the utilization of N-2 as the etching gas is associated with a lower degree of damage and also a lower electron accumulation at the surface of both InAs and InSb. (C) 1999 American Institute of Physics. [S0021-8979(99)07212-6].