Lw. Tu et al., SPATIAL DISTRIBUTIONS OF NEAR-BAND-GAP UV AND YELLOW EMISSION ON MOCVD GROWN GAN EPIFILMS, Physical review. B, Condensed matter, 58(16), 1998, pp. 10696-10699
Near-band-gap UV and yellow band emission from metal-organic chemical
vapor deposition grown GaN films on sapphires are investigated under l
aser excitation. The intensities of the UV and the yellow peaks increa
se at different rates as the entrance slit width of the spectrometer i
ncreases. The spatial distribution of the luminescence emission is ana
lyzed through the dependence of photoluminescence intensity on the sli
t widths of the spectrometer. The yellow emission originates from a sp
ot with a size about 1.5 times larger in diameter than the UV emission
. Using an absorption mechanism, a Lorentzian line-shape distribution
ft with the data gives estimated effective absorption coefficients of
47 cm(-1) for the UV signal at 364 nm and of 32 cm(-1) for the yellow
signal at 546 nm, which agrees perfectly with the ones from an exponen
tial decay fit. Dependence of UV-to-yellow peak ratio on the slit widt
hs of the spectrometer, and consistence with possible origins of yello
w luminescence is discussed. [SO163-1829(98)03132-4].