Effects of low-energy ion beam glancing angle nitridation on nGaAs surface and Co–nGaAs Schottky contact properties

Abstract

In this research, effects of low-energy nitrogen and argon ion beam irradiation at a glancing angle on chemical composition and morphology of the GaAs surface as well as electrical properties of Co–nGaAs Schottky contact are studied. Substantial reduction of the effective barrier height was observed. This reduction was explained by formation of the irradiation-induced thin n+ layer. This revealed that low effective barrier height and low noise Co–nGaAs Schottky contacts can be fabricated on GaAs by low-energy nitrogen ion beam irradiation of surface. On the other hand, GaAs surface irradiation by low-energy noble gas (argon) ion beam resulted in substantial increase of the low-frequency noise at liquid nitrogen temperature. Formation of a thin GaN layer as a result of the GaAs surface irradiation by low-energy nitrogen ion beam was observed by XPS. Experimentally registered decrease of the low-frequency noise (in the case of nitrogen irradiation) was explained in terms of the screening of irradiation-induced defects, passivation of dangling bonds at the GaAs surface nGaAs and increased surface and Schottky contact homogeneity due to the ion beam nitridation.