Modulation-doped (AlGa)As/GaAs quantum well structure with high electron sheet density

A single-sided modulation-doped 90 A quantum well with Al0.45Ga0.55As barriers has been realised using metalorganic vapour-phase epitaxy with selenium doping. Hall effect measurements give a sheet carrier density ns= 2.27 × 1012cm−2 and a mobility μ = 6050cm2V−1s−1 at 300 K. At 4.2 K, Shubnilcov-de Haas and quantum Hall effect measurements give ns = 1.52 × 1012cm−2 and μ = 1.28 × 105cm2V−1s−1. A persistent increase in ns to 2.00 × 1012cm−2 is observed at 4.2K by passing a large current through the sample for a short period of time.