Analytical Model Development for Unified 2D Electron Gas Sheet Charge Density of AlInN/GaN MOSHEMT

Abstract

Abstract-We have developed a unified analytical model for computation of 2D electron gas sheet charge density in AlInN/GaN metal-oxide-semiconductor high electron mobility transistor device structure. This model has been developed by incorporating the variation in lowest three energy sub-bands and Fermi level energy in the quantumwell with respect to gate voltage. We noticed that the dependency of lowest sub-band energy with Fermi energy having two fields, which are the lowest sub-band energy is greater and lesser than the Fermi level energy. According to these two fields, we have developed the fermi energy and sheet charge density expressions in each field. By combining each field of the models, developed a unified 2D electron gas sheet charge density model. The Fermi level and sheet charge density are interdependent in the model development. The developed model results are compared with TCAD simulation results and obtain a good consistency between them. This model is fitted to other metal-oxidesemiconductor high electron mobility transistor devices also with modifications in related physical values.

Analytical modeling of 2DEG with 2DHG polarization charge density drain current and small‐signal model of quaternary AlInGaN HEMTs for microwave frequency applications

“…4 The hole concentration however can be modulated by applying a potential to the surface or by increasing channel thickness in AlInN. Equations (11), (22), and (25) which are relating p s and n s help in confining the sheet carrier densities, p s =3.2 × 10 16 cm −3 in comparsion with experimentally reported data. 4 It is evident that, only after the 2DHG is depleted, the 2DEG concentration starts increasing.…”

“…When the electric field decreases in the QW subband, energy values decrease, then the difference in Fermi level increases and in consequence impacts the carrier density. 25 The relative energies between Fermi level and subbands show gradually an increase of relative energies (E F − E 0 ) and decrease (E F − E 1 ) with respect to applied gate potential. Figure 3 shows the comparison of sheet carrier density n s of the modeled AlInGaN barrier thickness of 35 nm with experimental data result of AlGaN barrier thickness of 26 and 21 nm.…”

“…[8][9][10][11] The total polarization effect directly causes changes in the charge density on the surface and influences the response of the carrier charge between channel and barrier interface (AlInGaN/AlInN). The governing first and second subband energy sheet carrier densities n s in region I and n s region II are determined using Equations (22) and (25).The sum of sheet carrier density (n s ) due to energy level in the first subband E 0 and second subband E 1 helps in improving surface charge concentration inside the QW. The obtained results for sheet carrier density n s with consideration for polarization charges show much accurate match with the reported expermential data of Anbuselvan et al and Mohanbabu et al 4,24 Figure 5A shows variation of sheet carrier density p s with respect to gate-to-source voltage V gs of modeled AlInGaN quarternary with experimentally reported AlInGaN barrier HEMT.…”