PHOTOCURRENT SPECTROSCOPY OF STRAINED-LAYER INGAAS-GAAS MULTIPLE QUANTUM-WELLS

The band configuration of the undoped strained-layer InxGa1-xAs(8 or 15 nm)-GaAs(15 nm) MQW with x=0.1, 0.15 and 0.2 have been investigated by photocurrent measurements at temperatures ranging from 10 to 300 K. The intersubband excitonic transitions 11H, 11L and 22H are observed. It is found that both electrons and heavy holes are confined to the InGaAs layers while light holes are confined to the GaAs layers. The photocurrent peak related to 2s or other excited states of a heavy-hole exciton is also observed and the binding energy thus obtained is about 8 meV. In addition the transitions between the confined subbands and continuum are also observed. The band offset Qv is derived in two different ways, which give Qv = 0.39 ± 0.03. © 1990.