GaAs surface low-dose irradiation pretreatment related reduction of Schottky barrier height. Real or effective?

Abstract Experimental data by Isothermal Capacitance Transient Spectroscopy (ICTS) have been applied to the investigation of correlation between the surface state density at the Si N- n GaAs interface and gallium arsenide surface irradiation pretreatment. The samples were pretreated by low-energy Ar ion-irradiation prior to deposition of the silicon nitride film. Upon irradiation, the shift of the density maximum of surface states from the familiar value E = 0.72 eV towards the conduction band has been detected. For initial samples the Fermi level pinning position was found to lie at E c − 0.68 eV, while it moved to value E c − 0.51 eV after irradiation. Hence, as revealed by ICTS examination, ion-irradiation pretreatment of the GaAs surface prior to contact deposition results in real, no merely effective reduction of the barrier height. The phenomenon was observed to hold both for MIS structures and Shottky contacts.