Author
Jun Suda, Electrical and Electronic Engineering, Graduate School of Engineering, Chukyo University
Keywords
Micro-Raman Spectroscopy, Tensile Stress, LO-phonon-plasmon-coupled (LOPC) mode, GaN, Ohmic electrode, FEM calculations
Abstract
In this study, Raman spectra for the EH2 mode in n-type GaN crystal with ohmic electrode (Ti/Al/Au) were measured by micro-Raman spectroscopy in the temperature range from room temperature to 200 ℃. Thermal stress change in the measured area (10μm×10μm) on the interface between GaN and the film electrode was analyzed by using the frequency shift for EH2 mode with the Raman biaxial stress coefficient by phonon deformation potential constant in the case of uniaxial tensile stress by three point bending test at room temperature. These experimental values of thermal stress change near the interface showed good agreement with those by FEM calculations qualitatively in the center of the electrode in this temperature range approximately. Also, we calculated the electron density, electron mobility, and resistivity values of the sample by spectra analysis using the dielectric dispersion for LOPC mode in n-type GaN at those temperature range. The resistivity values near the interface tended to increase significantly with increasing temperature in comparison with those far from the interface.