Abstract
We report the observation of a high-mobility, two-dimensional electron gas (2DEG) at the interface between a molecular beam epitaxial (MBE)-grown undoped In 0.53 Ga 0.47 As layer and a subsequent layer of MBE-grown, Si-doped In 0.48 Al 0.52 As. Peak mobilities of ∼92 000 cm 2 V -1 s -1 have been observed at 4.2 K. From Hall and Shubnikov-de Haas studies we have found that the 2DEG can be characterized by n ch = 6-8×10 11 cm -2 . In all cases we found two subbands to be occupied at N ch ≳4. 5×10 11 cm -2 .