ELECTRON-BEAM-INDUCED CURRENT MEASUREMENTS OF MINORITY-CARRIER DIFFUSION LENGTH IN GALLIUM NITRIDE

Minority carrier diffusion length in epitaxial GaN layers was measured as a function of majority carrier concentration and temperature. The diffusion length of holes in n-type GaN is found to decrease from 3.4 to 1.2 mu m in the doping range of 5x10(15)-2x10(18) cm(-3). The exper imental results can be fitted by assuming the Einstein relation and by the experimental dependence of hole mobilities on carrier concentrati on. The low injection carrier Lifetime of similar to 15 ns, used in th e tit, is largely independent of the doping level. The diffusion lengt h, measured for similar to 5x10(15) and 2 x 10(18) cm(-3) dopant conce ntrations, shows an increase with increasing temperature, characterize d by an activation energy E(a) of similar to 90 meV, independent of th e impurity concentration. (C) 1996 American Institute of Physics.