This study proposes an InAlAsSb/InP heterostructure field-effect transistor (HFET) grown by a low-pressure metallorganic chemical vapor deposition system. Its InAlAsSb Schottky layer and coupled delta-doped InP channels cause this HFET to exhibit high two- and three-terminal breakdown voltages. Mobility and two- dimensional electron gas concentration are increased. Additionally, this HFET does not exhibit the frequently observed parallel conduction and bell-shaped characteristics of conventional HFETs. The activation energy is also determined. (c) 2005 The Electrochemical Society. All rights reserved.