EFFECTS OF BAND-OFFSET AND NONPARABOLICITY ON THE EFFECTIVE-MASS OF 2-DIMENSIONAL ELECTRON GASES IN MODULATION-DELTA-DOPED GA0.47IN0.53AS-BASED HETEROSTRUCTURES

We present an investigation of electronic and optical properties of tw o-dimensional electron gases confined in modulation-delta-doped Ga0.47 In0.53As-based heterostructures by Shubnikov-de Haas measurement and o ptically detected cyclotron resonance (ODCR). Quantum oscillations cle arly show the occupation of the first two subbands. The Values of the effective masses obtained from ODCR measurements are considerably high er than the bulk data by 20-50 %. The theoretical prediction of the ef fect of nonparabolicity is insufficient to explain the experimental re sults. By choosing heterostructures with a very large difference in th e conduction-band offset, we clearly show that this discrepancy can be attributed to the effect of wave-function penetration into the barrie r material.