Capacitiveiy induced high mobility two-dimensional electron gas in undoped Si/Si_(1-x)Ge_x heterostructures with atomic-layer-deposited dielectric

摘要

The authors demonstrate that a high mobility two-dimensional electron gas can be capacitively induced in an undoped Si/Si_(1-x)Ge_x heterostructure using atomic-layer-deposited Al_2O_3 as the dielectric. The density is tuned up to 4.2 X 10~(11)/cm~2, limited by the gate leakage current. The mobility increases with the density rapidly and reaches 5.5 X 10~4 cm~2/V s at the highest density. The observation of well developed quantum Hall states and two-dimensional metal-insulator transition shows that the devices are suitable for two-dimensional electron physics studies.