Analytical modeling of AlGaN/AlN/GaN heterostructures including effects of distributed surface donor states

Abstract

In this paper, a physics based analytical model is presented for calculation of the two-dimensional electron gas density and the bare surface barrier height of AlGaN/AlN/GaN material stacks. The presented model is based on the concept of distributed surface donor states and the self-consistent solution of Poisson equation at the different material interfaces. The model shows good agreement with the reported experimental data and can be used for the design and characterization of advanced GaN devices for power and radio frequency applications.

Alx GaN1-x /AlN/GaN and DH-Alx GaN1-X /GaN HEMTs Threshold Voltage Model

“…Based on the concept of distributed surface donor states, it is assumed that a constant density of surface donor states with population of n 0 states per unit area per unit energy is available below a certain donor level of E d . This equates to the the number of empty surface donor states above the Fermi‐level which is further equivalent to n s and it can be written as …”

“…A few years ago, Goyal et al proposed a model for Schottky barrier height and 2DEG density in AlGaN/GaN and AlGaN/AlN/GaN heterostructures based on the idea of distributed surface donor states situated at the AlGaN top . They pointed out that the presence of a barrier layer with high aluminum concentration strongly impacts the ϕ b and resultant 2DEG density ( n s ).…”

Modeling charge density in AlGaN/AlN/InGaN/GaN-based double heterostructures including InGaN layer strain relaxation

“…It may be noted that if one sets the In mole fraction n=0 and the effect of E F is marginalized, equation (7) reverts to the expression developed for the bare AlGaN/AlN/GaN heterostructures [30]. Moreover, if one sets d AlN =0, equation (7) becomes the expression developed for the bare AlGaN/InGaN/GaN heterostructures [25].…”

“…The surface barrier height SBH in these DHs is discussed. It is already known how the use of an AlN spacer in an AlGaN/AlN/GaN heterostructure increases its SBH [30]. In an AlGaN/AlN/InGaN/GaN DH (d AlN =1 nm) and corresponding to (d AlGaN =17nm, m=0.25, and n=0.04) [35], the SBH is calculated to be 2.84 eV.…”

“…Comparison of the 2DEG density between the model prediction and the experimentally reported data[21,30,35] is shown (d AlN =1 nm). The parameter r is extracted for d InGaN =12 nm.…”