A compact drain current model for heterostructure HEMTs including 2DEG density solution with two subbands

•An explicit and accurate scheme to compute Fermi level and surface potential.•The surface potential model accounts for the two subbands in the quantum well.•A single-piece drain current model for HEMTs is developed.

An explicit and precise model for two dimensional electron gas (2DEG) charge density and Fermi level (EfEf) in heterostructure high electron mobility transistors (HEMTs) is developed. This model is from a consistent solution of Schro¨dinger’s and Poisson’s equations in the quantum well with two important energy levels. With these closed-form solutions, a unified surface potential calculation valid for all the operation regions is derived. With the help of surface potential, a single-piece drain current model is developed which is also capable of describing the current collapse effect by using a semi-empirical expression of source/drain access region resistances. Comparisons with numerical and measured data show that the proposed model gives an accurate description of EfEf and drain current in all regions of operation.