Deep Level Defects in Mg-Doped GaN


Deep level defects in Mg compensated GaN grown by metal-organic vapor phase epitaxy were investigated using photocapacitance spectroscopy measurements on Schottky barrier diodes Addition of magnesium resulted in the formation of a series of deep centers with optical threshold energies of 1.0, 1.2, 1.8, and 3.1 eV. Upon annealing the epitaxial GaN in nitrogen at 850°C the mid-gap levels disappeared and only the trapping level at 3.1 eV remained. The mid-gap levels are ascribed to Mg dopant complexes which may in part be responsible for low doping efficiency of Mg in the as-grown, doped GaN. The deep level at 3.1 eV commonly observed from all Mg-doped GaN most likely involves the Mg acceptor. The photo-excited state of the 3.1 eV level had relaxation times of the order of 103 sec at 295 K.

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This work was supported by the National Science Foundation Ceramics and Electronic Materials Program under grant number DMR-9302357. Extensive use of the facilities of the Materials Research Center at Northwestern University supported in part by the NSF under grant number DMR-9120521 is acknowledged.

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Correspondence to Gyu-Chul Yi.

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Yi, GC., Wessels, B.W. Deep Level Defects in Mg-Doped GaN. MRS Online Proceedings Library 423, 525–530 (1996).

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