Influence of temperature and drain current on source and drain resistances in AlGaN/GaN HEMTs

The behavior of source and drain resistances (R-S and R-D) has been studied for a wide range of drain currents at ambient temperatures from 150 to 500 K. Both parasitic resistances show an important increase as temperature rises, directly related to the reduction in the electron mobility. High drain currents also produce a non-linear increment of R-S and R-D, once the space-charge limited current is exceeded. Both temperature and drain current mechanisms have been modeled together by means of a simple equation, and a good agreement between simulations and measurements is found. Non-linear R-S and R-D allow a more accurate extraction of the intrinsic parameters, especially in the high drain current range. The use of variable parasitic resistances instead of their usually assumed constant values reveals higher intrinsic transconductance (g(m,int)) and C-gs. (C) 2011 Elsevier Ltd. All rights reserved.