INVESTIGATION OF THE INTERFACE QUALITY OF GAAS/ALGAAS HETEROSTRUCTURES

We report on optical and electrical properties of GaAs/AlGaAs heterostructures prepared by molecular beam epitaxy (MBE). For fixed Ga and As fluxes the damping of the oscillations of the reflection high energy electron diffraction (RHEED) pattern is strongly dependent on substrate temperature. The minimum of the damping of the intensity oscillations has been observed at 750°C. The best electrical properties of high electron mobility transistors (HEMT) have been found at this substrate temperature. The maximum electron mobility was 120000 cm2/Vs at 77 K for a spacer of 50 Å and an electron concentration of 1*1012 cm-2. For the presented quantum well (QW) structures we obtained the best results at a substrate temperature of 740°C. In photoluminescence we obtained a full width at half maximum (FWHM) for example for a 20 nm, 4.5 nm, 2 nm and 1 nm wide QW of 0.27 meV, 1.5 meV, 5 meV and 7 meV respectively. © 1990.