Hole-tunneling dynamics in biased GaAs/${\mathrm{Al}}_{0.35}$${\mathrm{Ga}}_{0.65}$As asymmetric double quantum wells

Hole tunneling is investigated by picosecond photoluminescence in two biased asymmetric double-quantum-well samples with different hole subband spacing. Spatially indirect excitons are observed above a threshold field. The energy difference between the wide-well direct and the crossed indirect exciton reveals the energy differences between hole subbands. Nonresonant tunneling with fast transfer times occurs above this threshold field without the contribution of optical phonons. Resonances in the hole-tunneling-transfer times occur at higher fields and are ascribed to mixing effects between heavy and light holes in adjacent wells.