Effect of Substrate Thinning on Temperature Rise in Ga2O3 Rectifiers

The low thermal conductivity of β -Ga 2 O 3 is a concern for the high-power switching applications envisaged for this ultra-wide bandgap semiconductor. In this work, we examine the effect of substrate thinning to reduce the temperature rise in rectifiers under high power conditions and also reduce the on-resistance. The Ga 2 O 3 substrates on which the rectifiers were fabricated were thinned from the original thickness of 630 μm to a lowest value of 50 μm and transferred to a brass heat sink. Experimentally, we observed that the on-resistance was reduced from 5.66 to 5.17 mΩ.cm 2 when thinning to 50 μm, in excellent agreement with simulations. The calculated peak temperature rise was roughly halved for rectifiers on such thin substrates over a broad range of power densities (500–1500 W.cm 2 ), a result supported by thermal imaging.