  The design of beta-Ga2O3-based modulation doped field effect transistors
(MODFETs) is discussed with a focus on the role of self-heating and resultant
modification of the electron mobility profile. Temperature- and
doping-dependent model of the electron mobility as well as temperature- and
orientation-dependent approximations of the thermal conductivity of beta-Ga2O3
are presented. A decrease in drain current was attributed to a
position-dependent mobility reduction caused by a coupled self-heating
mechanism and a high electric-field mobility reduction mechanism. A simple
thermal management solution is presented where heat is extracted through the
source contact metal. Additionally, it is shown that an undesired secondary
channel can form at the modulation doped layer that is distinguished by an
inflection in the transconductance curve.
