Chemical Vapor Deposition of Diamond Films on Patterned GaN Substrates via a Thin Silicon Nitride Protective Layer

Abstract

Integrating diamond films with GaN-based devices may enhance heat dissipation and thus improve device performance for high power loading. Direct deposition of diamond films on GaN layers has been hampered by GaN degradation in the chemical vapor deposition environment for diamond growth. In this work, three approaches were introduced to grow high-quality diamond films on patterned GaN substrates via a thin silicon nitride protective layer, that is, (i) a two-step process involving an initial rapid growth step, (ii) addition of nitrogen to hydrogen-based plasma to suppress reactions between GaN and hydrogen, and (iii) deposition in argon-based plasma. Continuous, adherent, and high-quality micro- and nanocrystalline diamond films were successfully deposited. All three approaches were effective in reducing plasma-induced GaN decomposition and etching, and in eliminating film cracks and delamination.