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Effect of boiling aqua regia on MOCVD and MBE p-type GaN surfaces and Cr/p-GaN interfaces

2011; Elsevier BV; Volume: 90; Linguagem: Inglês

10.1016/j.mee.2011.04.066

1873-5568

F. G. Kalaitzakis, Г. Константинидис, L. Sygellou, S. Kennou, S. Ladas, N. T. Pelekanos,

Ga2O3 and related materials

The effect of boiling aqua regia treatment on MOCVD and MBE p-GaN surface and p-GaN/Cr interface is examined with I–V measurements and X-ray photoelectron spectroscopy. The MBE p-GaN/Cr/Au contacts are of lower resistance in all cases, as compared to their MOCVD counterparts. Upon boiling aqua regia treatment, the surface of the MBE p-GaN material appeared to be more stable, as opposed to the increased sensitivity of the MOCVD one. As a result of the different behavior of the two samples surfaces was the fact that surface Fermi energy levels of MOCVD and MBE p-GaN moved towards opposite directions, which improved the contacts formed on the MOCVD sample in contrast to the MBE one, as confirmed by electrical characterization. Finally, the formation of Ga–Cr phase at the MOCVD p-GaN/Cr interface is detected, without any thermal treatment of the contacts. A possible formation mechanism which might explain the binary phase formation is presented and discussed.