MAGNETORESISTANCE EFFECT IN ALGAAS/GAAS TWO-DIMENSIONAL ELECTRON-GAS STRUCTURES AT ROOM-TEMPERATURE

Room temperature magnetoresistance measurements have been made on a number of AlGaAs/GaAs two-dimensional electron gas structures in fields of up to 7 Tesla. These wafers exhibit varying degrees of conduction in the AlGaAs in parallel with the 2-D electron gas which is formed at the heterojunction. By making the assumption of a single, energy-independent scattering time for each conducting channel, the magnetoresistance data are well fitted by the two band model, giving values of the sheet electron density in the 2-D electron gas at 300 K in with the results of Shubnikov-de Haas measurements at 4. 2 K, even in the presence of significant parallel conduction. An upper limit on the error associated with this assumption in the case of the 2-D electron gas can be estimated by studying samples with minimal parallel conduction.