Thermal annealing behaviour on Schottky barrier parameters and structural properties of Au contacts to n-type GaN

We have investigated the thermal annealing effects on electrical and structural properties of Au Schottky contacts on n-type GaN using current–voltage (I–V), capacitance–voltage (C–V), X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS) measurements. The calculated Schottky barrier height of the as-deposited Au/n-GaN diode was 0.85 eV (I–V) and 1.4 eV (C–V), respectively. However, after annealing at 300 °C it was found that the Schottky barrier height (SBH) slightly decreased to 0.77 eV (I–V) and 1.24 eV (C–V), and then slightly increased to 0.83 eV (I–V) and 1.30 eV (C–V) when the contact was annealed at 400 °C. With further increase in annealing temperature to 500 °C the barrier height was decreased and the respective values are 0.73 eV (I–V) and 1.02 eV (C–V). Based on the X-ray diffraction and RBS results, the formation of gallide phases at the Au/n-GaN interface could be the reason for variation in the Schottky barrier heights upon annealing temperatures

Data acquisition system using Matlab for deep level transient spectroscopy studies

204-209A microcontroller (AT89S8252) based data acquisition system has been developed for acquiring and processing the data from a home built deep level transient spectroscopy (DLTS)system. User friendly menu driven software has been developed in Matlab for selection of different DLTS measurement modes, data acquisition modes, channels (four channels) selection and number of data points on a single transient. It can be operated in two data acquisition modes namely scan mode and continuous mode. The scan mode is used to perform online analysis and continuous mode for offline data analysis. The developed software is also useful to operate the DLTS system in any one of the two operating modes namely boxcar mode or high resolution mode. The versatility of the data acquisition system is that the software developed can be used to obtain I-V characteristics using commercially available source meters. The paper also deals with the different wavelet decomposition methods for DLTS data acquisition and processing