EXTERNAL PHOTOLUMINESCENCE EFFICIENCY AND MINORITY-CARRIER LIFETIME OF (AL,GA)AS GAAS MULTI-QUANTUM-WELL SAMPLES GROWN BY MOLECULAR-BEAM EPITAXY USING BOTH AS2 AND AS4/
Ct. Foxon et al., EXTERNAL PHOTOLUMINESCENCE EFFICIENCY AND MINORITY-CARRIER LIFETIME OF (AL,GA)AS GAAS MULTI-QUANTUM-WELL SAMPLES GROWN BY MOLECULAR-BEAM EPITAXY USING BOTH AS2 AND AS4/, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 12(2), 1994, pp. 1026-1028
We report the results of measurement of the external photoluminescence
efficiency and minority carrier lifetime of a series of n - and p -ty
pe (AlGa)As-GaAs multi-quantum-well samples grown by molecular beam ep
itaxy, as a function of growth temperature in the range 600 to 700-deg
rees-C, using both As2 and As4. For equivalent growth conditions (subs
trate temperature and arsenic species) the minority carrier lifetimes
in n- and p-type samples are found to be the same. We suggest that the
lifetimes are determined by recombination via deep centers (possibly
oxygen-related) close to the (AlGa)As/GaAs interface. For an individua
l sample there is a good correlation between the variations in lifetim
e and external efficiency across a wafer, the variation being ascribed
to temperature differences resulting from poor wetting with In. A muc
h weaker correlation is observed from sample to sample, suggesting tha
t there are factors other than the internal photoluminescence efficien
cy that determine the light emitted from the surface. We tentatively s
uggest that morphology may be a factor.