Effects of the Low Energy Ion Beam Nitridation on GaAs Surface Structure and Electrical Characteristics of Au-nGaAs and Co-nGaAs Schottky Contacts

Abstract

Effects of the 65 eV – 320 eV energy nitrogen ion beam irradiation on surface structure and electrical properties of the
Au -GaAs and Co-GaAs Schottky contacts were investigated. Formation of the thin GaN or GaAsxN1-x type layer as a
result of the GaAs surface 65 eV and 320 eV nitrogen ion beam treatment was observed. Thickness of this layer
increased with increase of the ion energy and ion current density. Ion beam nitridation in all cases resulted in decreased
effective barrier height of Au-nGaAs and Co-nGaAs Schottky contacts. Low frequency noise of the irradiated Schottky
contacts measured at room and liquid nitrogen temperatures in all cases exceeded noise of the reference samples.
Current-voltage (I-V) characteristics of Au-GaAs and Co-GaAs fabricated on nitrogen ion beam irradiated GaAs surface
were very similar. It means, that I-V characteristics of these contacts depends on properties of the irradiation modified
GaAs surface layer. There were revealed, that the influence of the nitrogen ion beam irradiation on electrical
characteristics of the Schottky contacts increases with increase of the ion energy, ion current density and treatment time.
GaAs Schottky contact low frequency noise level, non-ideality factor and effective barrier height increased as a result of
the ion irradiation angle change from glancing (oblique) to the normal.