K. Bacher et al., MOLECULAR-BEAM EPITAXY OF STRAIN-COMPENSATED INGAAS GAASP QUANTUM-WELL INTERSUBBAND PHOTODETECTORS/, Journal of crystal growth, 175, 1997, pp. 977-982
We report on the growth of quantum well intersubband photodetectors (Q
WIPs) with InGaAs wells grown on GaAs. Arsenic species and substrate t
emperature were varied to investigate their effects on the photolumine
scence (PL) and lattice relaxation of 40 period InGaAs/GaAs QWIP sampl
es. Both PL intensity and lattice relaxation decreased with decreasing
substrate temperature - the PL dropping steeply below 500 degrees C a
nd the relaxation dropping gradually below 470 degrees C. In all cases
examined, however, the relaxation was at least 33% as measured by asy
mmetric (115) five crystal X-ray scans. Introducing a small percentage
of phosphorous into the barriers to partially strain-compensate the s
tructure was found to dramatically reduce the lattice relaxation while
maintaining the highest PL intensity. Comparison of this strain-compe
nsated InGaAs/GaAsP QWIP with the optimized InGaAs/GaAs QWIP revealed
that the dark current was reduced by a factor of 4 while the photocurr
ent remained virtually unchanged resulting in an increase in the backg
round limited operating temperature by approximately 3 K.