Charge state effect on near-surface damage formation in swift heavy ion irradiated InP

Abstract

Irradiation of single-crystalline InP with large fluences of swift heavy ions (SHI’s) causes formation of amorphous layers within the depth range of dominating electronic energy loss. However, unlike the bulk, a thin surface layer (tens of nanometers) remains almost undamaged. In the present paper this peculiarity is studied in more detail. One can make two plausible suppositions: (a) either the surface acts as an efficient sink for defects produced by SHI irradiation near the surface (i.e., they move towards the surface and annihilate there) or (b) SHI energy deposition within the thin surface layer is lower than that in the bulk. The latter effect takes place, for example, if the initial charge of the impinging ions is lower than the mean equilibrium one in the target bulk. Our results give an indication of a dominating influence of the SHI charge state. No noticeable influence of the surface as a sink for defects was observed.