Isolation characteristics of GaN mesas on diamond substrates fabricated using the surface-activated bonding

Abstract The electrical isolation of nitride devices in highly integrated circuits is essential for their normal operation. We fabricated fully isolated GaN mesas on diamond substrates by transferring an epitaxially grown n-GaN layer using the surface-activated bonding and performing mesa etching to expose the underlying diamond surface. The leakage currents between the isolated GaN mesas were comparable to the currents observed between contacts directly formed on diamonds, and markedly smaller than those between fully isolated mesas on semi-insulating 4H-SiC or Si substrates as well as partially isolated mesas on Si or polycrystalline diamond substrates. The activation energy of the current between the on-diamond isolated mesas was larger than that of the current between the on-SiC isolated mesas. These results indicate that isolated nitride mesas on diamonds are promising for realizing nitride devices with excellent isolation properties.