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

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 1995-12, Vol.35 (1), p.203-207
• Main Authors: Evans, R.J., Burke, T.M., Burroughes, J.H., Grimshaw, M.P., Ritchie, D.A., Pepper, M.
• Format: Article
• Language: English
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Gallium arsenide; Miscellaneous; Molecular beam epitaxy; p-n junction; Semiconductor devices; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/0921-5107(95)01441-1

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 × 10 11 cm −2 and mobility 2.4 × 10 4 cm 2V −1s −1 in the dark assuming the 2DHG extends over the geometric width of the facet. The (100) 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 Al 0.3Ga 0.7As (undoped), 40 nm Al 0.3Ga 0.7As silicon doped (10 18cm −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. Here we 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’.