Diamond-BN Heterojunctions for High Power Devices: The Ultimate HEMT?

This review explores the properties of diamond and boron nitride as a promising materials combination for high electron mobility transistors, HEMTs. These ultra-wide bandgap materials exhibit excellent electronic properties as well as high thermal conductivity for superior heat dissipation. The lattice mismatch between cubic boron nitride (c-BN) and diamond is $\sim \mathbf{1. 4 \%}$ allowing for the epitaxial growth of heterojunction devices. However, to demonstrate a viable c-BN/diamond HEMT technology a number of significant challenges remain, including: the epitaxial growth of single crystal heterojunctions on large area substrates; control of phosphorus dopant incorporation for n-type channels; and achieving low specific contact resistance to source and drain regions. There has been recent progress towards achieving these goals, paving the way for a new generation of high-power electronic devices for DC and RF applications.