Electrical properties of metalrGaN and SiO rGaN interfaces and 2 effects of thermal annealing

Properties of metalrn-GaN Schottky and PCVD-SiO2rn-GaN interfaces, including the effect of thermal annealing, have been investigated by I–V–T, C–V and C–t measurements. I–V–T characteristics of the Schottky diodes indicate that reported large discrepancies in the Schottky barrier height SBH. between I–V and C–V measurements, scattered Richardson constants, and I–V shoulders are well explained by superposed current arising from ‘‘surface patches’’ with low SBHs. A low-temperature annealing in N2 is highly effective to improve the uniformity of the SBH. For the as-deposited SiO2rn-GaN sample, the interface Fermi level locates at about 0.2 eV from the conduction band edge under thermal equilibrium condition, and the value increased to 0.5 eV after annealing in H2 at 5008C. A relatively small band bending was also confirmed from C–t measurement. The minimum interface state density of 2=1011 cmy2 eVy1 for the as-deposited interface reduced to one-third after the annealing. q2000 Elsevier Science B.V. All rights reserved.