Fm. Steranka et al., TEMPERATURE-DEPENDENT MINORITY-CARRIER LIFETIME MEASUREMENTS OF RED ALGAAS LIGHT-EMITTING-DIODES, Journal of electronic materials, 24(10), 1995, pp. 1407-1412
Electroluminescent decay and internal quantum efficiency measurements
are made as a function of temperature on two double heterostructure Al
GaAs light emitting diodes (LEDs) that emit in the visible (red) porti
on of the spectrum. The electroluminescent lifetimes increase by more
than a factor of ten and the internal quantum efficiency falls by a fa
ctor of three as the temperature is raised from 90 to 400K. By analyzi
ng the data with a model that accounts for the transfer with increasin
g temperature of the minority-carrier electrons from the direct-gap to
the indirect-gap minima in the p-type active layer of these near-cros
sover LEDs, values for the radiative and nonradiative lifetimes as a f
unction of tenlperature are obtained. A fit to the radiative-lifetime
data results in an estimate of 1.3 x 10(-10) cm(3)s(-1) for the room-t
emperature radiative recombination coefficient of Al0.39Ga0.61As, whic
h is very similar to values reported for GaAs. The nonradiative lifeti
mes are found to be nearly independent of temperature from 220 to 400K
and provide upper limits of 940 and 1250 cms(-1) for the interface re
combination velocities of the two samples. These values are roughly an
order of magnitude lower than any previously reported values for high
-Al-content (x > 0.3) AlxGa1-xAs heterostructures.