TiO thin films on GaN(0001)

Abstract

Physical features of titanium monoxide layers deposited on p‐GaN(0001) substrate are reported in this paper. TiO was deposited under ultrahigh vacuum at room temperature. As revealed by scanning tunneling microscopy (STM) the deposit had grainy structure. The X‐ray and ultraviolet photoelectron spectroscopy (XPS/UPS) studies have shown that, depending on the altered by annealing morphology of the TiO‐based film, work function of the system underwent changes and electronic structure of the deposit displayed metallic character. The formation of specific TiN and ON bonds is confirmed by spectroscopic techniques. Electrical conductance of the TiO‐based/p‐GaN interface has been studied by current‐sensing atomic force microscopy (CS‐AFM) with Au‐covered tip. Formation of ohmic nano‐contacts on p‐GaN surfaces was observed over whole probed surface. The contacts were homogeneous in contrast to the grainy structure of TiO‐based film. The results suggest that TiO may be considered as an intermediate semiconducting layer (ISL) useful for p‐GaN electrical contact engineering.