Temperature‐dependent profile of the surface states and series resistance in (Ni/Au)/ AlGaN/AlN/GaN heterostructures

The profile of the interface state densities ( N ss ) and series resistances ( R s ) effect on capacitance–voltage ( C – V ) and conductance‐voltage ( G /ω– V ) of (Ni/Au)/Al x Ga 1− x N/AlN/GaN heterostructures as a function of the temperature have been investigated at 1 MHz. The admittance method allows us to obtain the parameters characterizing the metal/semiconductor interface phenomena as well as the bulk phenomena. The method revealed that the density of interface states decreases with increasing temperature. Such a behavior of N ss can be attributed to reordering and restructure of surface charges. The value of series R s decreases with decreasing temperature. This behavior of R s is in obvious disagreement with that reported in the literature. It is found that the N ss and R s of the structure are important parameters that strongly influence the electrical parameters of (Ni/Au)/Al x Ga 1− x N/AlN/GaN( x = 0.22) heterostructures. In addition, in the forward bias region a negative contribution to the capacitance C has been observed, that decreases with the increasing temperature. Copyright © 2010 John Wiley & Sons, Ltd.