Band gap state formation in InP (110) induced by 10 and 100 eV argon ion bombardment

The dynamical process of surface band bending induced by ion bombardment as a function of ion fluence and energy has been studied with a special low e nergy ion beam system and an x-ray photoelectron spectrometer. It was found that 10 and 100 eV Ar+ bombardment of n- and p-InP (110) samples, which we re prepared in ultrahigh vacuum by in situ cleavage of InP (100) bars, move d their surface Fermi levels to a common pinning position 0.95 eV above the valence-band maximum. The observed surface band bending was attributed to the displacement damage in the near-surface region induced by the ion bomba rdment. A quantitative analysis of the band bending data as a function of i on fluence showed that for the 10 eV Ar+ bombardment the formation of ioniz ed surface states at a density of about 1x10(12)/cm(2) in the band gap of I nP was induced by an ion fluence of 5x10(16)/cm(2). As expected, an increas e of bombardment energy from 10 to 100 eV greatly raised the formation prob ability of surface defects. The results imply that very brief plasma exposu re is sufficient to cause surface damage to a semiconductor that is severe enough to affect the device performance of the semiconductor. (C) 1999 Amer ican Institute of Physics. [S0021-8979(99)03819-0].