Suppressed carrier density for the patterned high mobility two-dimensional electron gas at γ-Al2O3/SrTiO3 heterointerfaces

The two-dimensional electron gas (2DEG) at the non-isostructural interface between spinel gamma-Al2O3 and perovskite SrTiO3 is featured by a record electron mobility among complex oxide interfaces in addition to a high carrier density up to the order of 10(15) cm(-2). Herein, we report on the patterning of 2DEG at the gamma-Al2O3/SrTiO3 interface grown at 650 degrees C by pulsed laser deposition using a hard mask of LaMnO3. The patterned 2DEG exhibits a critical thickness of 2 unit cells of gamma-Al2O3 for the occurrence of interface conductivity, similar to the unpatterned sample. However, its maximum carrier density is found to be approximately 3 x 10(13) cm(-2), much lower than that of the unpatterned sample (similar to 10(15) cm(-2)). Remarkably, a high electron mobility of approximately 3600 cm(2) V-1 s(-1) was obtained at low temperatures for the patterned 2DEG at a carrier density of similar to 7 x 10(12) cm(-2), which exhibits clear Shubnikov-de Haas quantum oscillations. The patterned high-mobility 2DEG at the gamma-Al2O3/SrTiO3 interface paves the way for the design and application of spinel/perovskite interfaces for high-mobility all-oxide electronic devices. Published by AIP Publishing.