H. Tsuchiya et al., INFLUENCE OF AS AUTODOPING FROM GAAS SUBSTRATES ON THICK CUBIC GAN GROWTH BY HALIDE VAPOR-PHASE EPITAXY, JPN J A P 2, 37(5B), 1998, pp. 568-570
GaN layers were grown on (001) GaAs substrates by halide vapor phase e
pitaxy (HVPE) on either a high-quality cubic buffer layer grown by met
alorganic molecular beam epitaxy (MOMBE) or a HVPE buffer layer on bot
h sides of the substrate. Though a high-quality cubic GaN (cubic compo
nent : more than 99% for 2 mu m thick layer) was grown on the MOMBE bu
ffer layer, the photoluminescence intensity was less than that of the
layer grown on the HVPE buffer layer by about two orders of magnitude.
This was found to be due to arsenic (As) autodoping from the back sid
e of the GaAs substrate. The As autodoping decreased the optimum growt
h temperature of cubic GaN by about 50 degrees C. The hexagonal compon
ent increased with an increase in the growth thickness, independent of
the initial cubic purity of the grown layer, suggesting that influenc
e of the As autodoping decreased with an increase in the growth thickn
ess.