论文信息 - Band line-up and mechanisms of current flow in n-GaN/p-SiC and n-AlGaN/p-SiC heterojunctions

Band line-up and mechanisms of current flow in n-GaN/p-SiC and n-AlGaN/p-SiC heterojunctions

The properties of n-GaN/p-SiC and n-AlGaN/p-SiC heterojunctions (HJ) prepared by hydride vapor phase epitaxy (HVPE) on 4H SiC substrates are reported. It is shown that the GaN/p-SiC HJ is staggered type II with the conduction bandoffset and the valence bandoffset values, respectively, ΔEc=−0.49 eV and ΔEv=0.65 eV. When changing GaN for AlGaN with Al mole fraction of x=0.25–0.3 the band alignment becomes normal type I with ΔEc=0.2 eV and ΔEv=0.6 eV. Current–voltage characteristics of both heterojunctions bear evidence of strong tunneling via defect states. The tunneling was found to be more pronounced in the AlGaN/SiC HJs even though these showed no evidence of formation of dark line defects at the interface, in contrast to GaN/SiC.

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