Metal-(n) AlGaAs-GaAs two-dimensional electron gas FET

Theoretical calculations have been developed for a two-dimensional electron gas FET (TEGFET) constituted by a AlGaAs (n)-GaAs (n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> or p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> ) heterostructure in which the Schottky gate is deposited on the AlGaAs(n) top layer. The theory takes into account: i) the subband splitting in the two-dimensional electron gas (2-DEG); and ii) the existence of an undoped AlGaAs spacer layer which has been found to enhance the electron mobility. The sheet carrier concentration of the TEGFET has been calculated, and a simple analytical formula has been established for the charge control in large and small gate FET.