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Optical time-of-flight measurement of carrier transport in GaAs/Al x Ga1− x As and In0.53Ga0.47As/In0.52Al0.48As multiquantum wells

1992; American Institute of Physics; Volume: 60; Issue: 12 Linguagem: Inglês

10.1063/1.107269

1520-8842

Sandeep Gupta, L. Davis, P. Bhattacharya,

Photonic and Optical Devices

An all-optical time-of-flight technique is used for measuring perpendicular carrier transport in semiconductor heterostructures and multiquantum wells (MQWs). This technique is based on measuring a change in surface reflectance due to the absorption nonlinearities induced by the carriers, and has a temporal resolution of ∼1 ps. Typical results on a GaAs/AlxGa1−xAs MQW and an In0.53Ga0.47As/In0.52Al0.48As MQW are compared. The observed fast transport times can only be explained by a field-dependent carrier emission out of the quantum well, after which transport through the continuum states can occur. Due to larger barriers in the In0.53Ga0.47As/In0.52Al0.48As system, this intrinsic limit to transport is much larger, and hence these devices are observed to be slower than their GaAs/AlxGa1−xAs counterparts.