Front-side diamond deposition on the GaN membranes

We present technological issues in the deposition of diamond films on the GaN membranes. Many wrinkles and the thicker diamond layer were observed at the membrane centre and poor quality diamond outside the membrane area. The deflection of the membranes were analyzed by a bulging method using white light interferometry. The membrane bending was discussed in the terms of temperature gradient and mismatch of thermal expansion coefficients of materials. Optimized technological procedure was proposed to obtain both-side diamond-coated GaN membranes with minimized effect of wrinkling and induced residual stress.