Modeling of hetero-interface potential and threshold voltage for tied and separate nanoscale InAlAs–InGaAs symmetric double-gate HEMT

This paper presents an approximate solution of a 2-D Poisson’s equation in the channel region, based on physical correspondence between MOSFET and HEMT, with the approximation that the vertical channel potential distribution is a cubic function of position to study not only tied gate but separate gate bias conditions as well. An analytical expression for both front and back heterointerface potential is derived and threshold voltage is obtained iteratively from the proposed potential model. The threshold voltage behavior for tied and separated double-gate HEMT is investigated for various device dimensions. The back gate effect of the separated double gate HEMT is investigated for the depleted back channel only. The results obtained are verified by comparing them with simulated and experimental results.