DLTS AND PHOTOLUMINESCENCE ON-WAFER MAPPING ANALYSES FOR ALGAAS/GAAS HETEROJUNCTION BIPOLAR-TRANSISTORS

The on-wafer mapping of the current gain in AlGaAs/GaAs heterojunction bipolar transistors (HBTs) has quite a close correlation with that of DLTS signals from the emitter/base junction region and with that of band-edge photoluminescence from the flat band emitter layer. It is found that the deep level with an activation energy around 0.6 eV, assigned as primarily ME6 or ME7, probably acts as an effective recombination center at the junction region and reduces the current gain of the transistors. It is also shown that the photoluminescence measurement is a promising method for nondestructive evaluation of the recombination centers in HBTs. © 1990.