Delta-Doped β-(Al0.17Ga0.83)2O3/Ga2O3 Double-Channel Heterostructure MODFETs

Abstract

Herein, in delta-doped β-(AlxGa1–x)2O3/β-Ga2O3 heterostructures, the 2D electron gas (2DEG) density is mainly limited by the low conduction-band offset at the heterointerface. Double-channel heterostructures may be a candidate solution for enhancing the 2DEG density in these heterostructures. In this study, the output characteristics, transfer, transconductance, and off-state current characteristics of delta-doped β-(Al0.17Ga0.83)2O3/β-Ga2O3 double-channel heterostructure modulation-doped field-effect transistors (MODFETs), including the effects of an ultrathin spacer layer and a back-barrier layer, are numerically evaluated. The electrical characteristics of the proposed double-channel heterostructure MODFET are compared with those of a single-channel heterostructure MODFET. The proposed double-channel heterostructure MODFET shows a maximum drain current of 133.7 mA mm−1 and a g m peak of 40 mS mm−1, which are higher than those in the single-channel case. The calculated threshold voltage is −3.45 V. The dependence of the Si δ-doping density in the second barrier and channel layer thickness on the electrical characteristics of the proposed device is evaluated and discussed. A β-(Al0.17Ga0.83)2O3/β-Ga2O3 superlattice back-barrier structure is also implemented in delta-doped β-Ga2O3-based heterostructure MODFETs to improve their off-state characteristics for the first time. © 2022 Wiley-VCH GmbH.