High-Power GaN Electronic Devices.

Gallium Nitride (GAN) and related materials (especially AlGaN) recently have attracted a lot of interest for applications in high-power electronics capable of operation at elevated temperatures and high frequencies. The A1GalnN system offers numerous advantages. These include wide bandpass, good transport properties, the availability of heterostructures (particularly AlGaN/GaN), the experience base gained by the commercialization of GaN-based laser and light-emitting diodes and the existence of a high growth rate epitaxial method (hydride vapor phase epitaxy, HVPE) for producing very thick layers or even quasisubstrates. These attributes have led to rapid progress in the realization of a broad range of GaN electronic devices. Al[subx]Ga[sub1-x] N (x=0 ∼ .25) Schottky rectifiers were fabricated in a lateral geometry employing F-implanted guard rings and rectifying contact overlap onto an SiO[sub2] passivation layer. The reverse breakdown voltage (V[subB]) increased with the spacing between Schottky and ohmic metal contacts, reaching 9700 V for Al[sub0.25]Ga[sub0.75]N and 6350 V for GaN, respectively, for 100-[tm gap spacing. Assuming lateral depletion, these values correspond to breakdown field strengths of ≤9.67 x 10[sup5] Vcm[sub-2], which is roughly a factor of 5 lower than the theoretical maximum in bulk GaN. The figure of merit (V[subB])²/R[subON], where R[subON] is the on-state resistance, was in the range 94 to 268 MWcm[sup-2] for all the devices. Edge-terminated Schottky rectifiers were also fabricated on quasibulk GaN substrates grown by HVPE. For small-diameter (75 µm) Schottky contacts, Vs measured in the vertical geometry was -700V, with an on-state resistance (R[subON]) of 3 mωcm², producing a figure-of-merit V[subB][sub2]/R[subON] of 162.8 MW-cm². GaN p-i-n diodes were also fabricated. A direct comparison of GaN p-i-n and Schottky rectifiers fabricated on the same GaN wafer showed higher reverse breakdown voltage for t [ABSTRACT FROM AUTHOR]