Pt Schottky contacts to n -GaN formed by electrodeposition and physical vapor deposition

Electrodeposited, dc magnetron sputtered, and electron beam evaporated Pt contacts to n-GaN (n=1.5×1017 cm-3) are reported. All contacts were rectifying in the as-deposited condition, and values of the barrier height were determined by current-voltage (I-V) and capacitance-voltage (C-V) measurements. The influence of deposition conditions on the electrical characteristics of the sputtered and electrodeposited Pt contacts was further studied. Additionally, a dependence of the barrier height with time following deposition is shown. Taking into consideration all parameters of this study, the barrier height could differ by as much as 0.65 eV by I-V measurements and 0.64 eV by C-V measurements, with I-V and C-V barriers as high as 1.43 and 1.57 eV, respectively. Reverse current densities are reported for a -5 V bias with the highest and lowest median values differing by a factor of 104 as a result of the different deposition conditions. The electrical properties are believed to be strongly influenced by the presence of electrically active defects introduced during metal deposition. Deep level transient spectroscopy data support this hypothesis.