Influence of high-index GaAs substrates on the 2D electron density of δ-doped pHEMT with an additional In_xGa_1-xAs (x > 0.15) thin layer embedded in the channel

Laboratoire de Physique des Semiconducteurs et des Composants Électroniques, Faculté des Sciences de Monastir, avenue de l'Environnement, 5000 Monastir, Tunisia

Corresponding author: boulotf@yahoo.fr

Received: 10 May 2004
Accepted: 7 October 2004
Published online: 21 December 2004

Abstract

In this paper, we report the theoretical predictions of a high-index GaAs substrate ((111)A and (311)A) on the subband structure and thereafter on the 2D electron density of Si δ-doped Al_0.33Ga_0.67As/In_0.15Ga_0.85As/GaAs pseudomorphic high electron mobility transistor (pHEMT) with an additional In_xGa_1-xAs (x > 0.15) thin layer embedded in the channel. We have seen that the electronic structures and the electron density are quite sensitive to the additional In_xGa_1-xAs (x > 0.15) layer thickness, indium composition and to their position in the channel. An optimal position of the additional In_xGa_1-xAs layer was found to be corresponding to the maximum of the first eigen envelope function for the different growth directions. We report that the optimised electron density is obtained in the structure grown on (111)A GaAs substrate. In this case the electron transfer is significantly higher than those grown on (311)A and (001) GaAs substrates respectively.