ELECTRON EFFECTIVE-MASS DETERMINATION IN ASYMMETRIC MODULATION-DOPED FIELD-EFFECT TRANSISTOR HETEROSTRUCTURES USING INXGA1-XAS QUANTUM-WELLAND INAS-GAAS SUPERLATTICE CHANNELS

Cyclotron resonance and photoluminescence measurements have been perfo rmed on two types of modulation-doped field-effect transistor heterost ructures having their bidimensional channel based, respectively, on an InxGa1-xAs quantum well and an InAs-GaAs short-period superlattice. A linear dependence of the electron effective mass as a function of ind ium content of the channel was obtained from cyclotron resonance measu rements. For a given average value of the indium content, the effectiv e mass in the InAs-GaAs short-period superlattice channel is found to be systematically higher than that obtained in structures with an allo y-based channel. This is attributed to larger nonparabolic effects in the former case. In our theoretical model, the electron and heavy hole energy levels and the electron wavefunction are determined self-consi stently and used to estimate the nonparabolic corrections that apply t o the effective mass deduced from cyclotron resonance measurements. (C ) 1998 Academic Press Limited.