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The electron mobility and compensation in n-type GaN

1998; IOP Publishing; Volume: 13; Issue: 3 Linguagem: Inglês

10.1088/0268-1242/13/3/010

1361-6641

John Orton, C. T. Foxon,

Semiconductor materials and devices

A literature study of the electron mobility in n-type GaN suggests that there is a wide range of epitaxial samples with carrier densities ranging from to which show an approximately constant compensation ratio . The purpose of this paper is to suggest a simple model of auto-compensation, based on native defects in GaN, which provides an explanation of this observation. Using theoretical predictions of Neugebauer and van der Walle concerning the formation energies of native defects, we demonstrate that a constant value of C implies a singly charged compensating acceptor. We compare this case with that of Se-doped GaN, which shows evidence for compensation by triply charged acceptors, and then demonstrate how co-existing singly and triply charged acceptors can provide an explanation of all the experimental data. The nature of the singly charged defect is unknown at present but we speculate that it might take the form of a complex of a single gallium vacancy partly neutralized by two donors, the complex being favoured by Coulomb attraction between the species.