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 In Sb surfaces induced by low-energy N-2 and Ar ion beam etching (IBE) were in vestigated as a function ion energy (less than or equal to 500 eV) using Ra man spectroscopy. A drastic enhancement of the electron concentration in th e near surface region of both materials independent of the ion energy and t he process gas was observed. From Raman measurements in different polarizat ion configurations it can be concluded that the electron accumulation obser ved after IBE is inherently related to the process-induced structural defec ts. The degree of structural damage and the carrier concentration in the ne ar surface region increase for higher ion energies. By controlled, subseque nt removal of the damaged surface layer using wet etching, the depth profil e of the structural and electronic damage in InAs was determined. This proc edure reveals that the structural and electronic damage extends about 100 n m into the material. Nevertheless, it can be recognized that the utilizatio n 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].