AlGaAs/GaAs quantum wells and Si-doped GaAs layers grown by molecular beam epitaxy (MBE) with water cooling system are characterized by photoluminescence and Hall effect measurements. The photoluminescence spectra from 3 nm and 8 nm thick GaAs quantum wells are in good agreement with theoretically calculated values at 4.2 K. Obtained carrier concentrations are 79 × 10
17/cm
3 with the mobilities larger than 2000 cm
2/V s at 300 K, which shows the background impurity concentration less than 1 × 10
17/cm
3. It is found that Al evaporation is remarkably effective for selective gettering of O
2 and H
2O in the system.
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