A hole facet wire formed by MBE regrowth over an ex-situ patterned GaAs substrate

The transport properties of a series of long (5–100 μm) channels formed by a novel technique has been investigated at low temperatures. The wire is formed by growing a quantum well structure over a patterned (100) substrate which is etched to expose the (311)A plane on the side-wall face. In our initial structures we have observed a narrow two dimensional hole gas (2DHG) with a carried concentration of 2.5 × 1011 cm−2 and mobility 2.4 × 104 cm2V−1s−1 in the dark assuming the 2DHG extends over the geometric width of the facet. 00) GaAs substrate is patterned using standard photolithographic techniques and etched using a buffered hydrofluoric acid based etch to expose a 4.8 μm wide facet, the (311)A plane. The wafer is cleaned immediately prior to reloading into the molecular beam epitaxy (MBE) growth chamber. The wafer is then regrown with a 140 nm buffer layer, a 60 nm GaAs quantum well, 20 nm Al0.3Ga0.7As (undoped), 40 nm Al0.3Ga0.7As silicon doped (1018cm−3) and a 10 nm GaAs cap layer. Owing to the amphoteric doping nature of silicon in GaAs, a 2DHG is formed on the narrow (311)A facet and a two dimensional electron gas (2DEG) is formed on the corresponding (100) planes surrounding the (311)A facet. e will report on our ongoing experiments enlarging on our initial two terminal characterization of the facet 2DHG. Applying a positive bias to the 2DEG on either side of the narrow facet results in squeezing of the 2DHG, in effect, the 2DEG acts as an ‘electron-gate’.