High-quality two-dimensional electron gas inAlxGa1-xAs/GaAs heterostructures by LP-OMVPE

A combination of high mobility and high sheet carrier density in Al_xGa_1-xAs/GaAs two-dimensional electron gas (2DEG) elements was obtained by low-pressure organometallic vapor phase epitaxy (OMVPE). The sheet charge densities (n_s) and mobilities (μ) at 77 K are 1.2×10¹²/cm² and 90000 cm²/V-s for single-channel, and 2.0× 10¹²/cm² and 64500 cm²/V-s for double-channel elements, respectively. Strong correlations between the photoluminescence spectrum of the Al_xGa_1-xAs layers and the 2DEG mobility were found. The 2DEG elements were used as mixers and detectors at millimeter wavelengths. Mixing at 94 GHz with a 1.7-GHz IF bandwidth and detection of signals as high as 238 GHz under a magnetic field were achieved with these devices