Simulation and optimization of GaN-based metal-oxide-semiconductor high-electron-mobility-transistor using field-dependent drift velocity model

Abstract

Undoped GaN-based metal-oxide-semiconductor high-electron-mobility-transistors (MOS-HEMTs) with atomic-layer-deposited Al2O3 gate dielectrics are fabricated with gate lengths from 1 μm up to 40 μm. With a two-dimensional numerical simulator, we report simulation results of the GaN-based MOS-HEMTs using field-dependent drift velocity model. A developed model, taking into account polarization-induced charges and defect-induced traps at all of the interfaces and process-related trap levels of bulk traps measured from experiments, is built. The simulated output characteristics are in good agreement with reported experimental data. The effect of the high field at the drain-side gate edge and bulk trap density of GaN on the output performance is discussed in detail for the device optimization. AlGaN/GaN/AlN quantum-well (QW) MOS-HEMTs have been proposed and demonstrated based on numerical simulations. The simulation results also link the current collapse with electrons spreading into the bulk, and confirm that a better electron localization can dramatically reduce the current collapse for the QW-MOS-HEMTs. Due to the large band edge discontinuity and effective quantum confinement of the AlGaN/GaN/AlN quantum well, the parasitic conduction in the bulk is completely eliminated.

Low on-resistance diamond field effect transistor with high-k ZrO2 as dielectric

“…According to the k value of 5.4 and the thickness of 4.0 nm for the ALD-Al 2 O 3 on the H-diamond (Data shown in the supporting information), the k value for the single SD-ZrO 2 can be calculated to be as large as 15.4. The C-V curve shows small flat band voltage ( V FB ) shift and small stretch-out32 in the depletion region, which implies low fixed and trapped charge densities in the SD-ZrO 2 /ALD-Al 2 O 3 /H-diamond structure3334. Based on the C-V curve and profiling technique1335, the 2DHG density as a function of depth from the ALD-Al 2 O 3 /H-diamond interface to the H-diamond epitaxial layer can be determined, which is shown in Fig.…”

Donor‐Like Surface Traps on Two‐Dimensional Electron Gas and Current Collapse of AlGaN/GaN HEMTs

“…The drain current collapse effect in these devices is a serious obstacle at the present stage to further improve device performances [ 6 – 8 ]. Some efforts have been made to explore the mechanisms of drain current collapse, such as self-heating [ 9 – 11 ], trapping [ 3 ], and surface states [ 12 – 15 ]. The bulk traps in AlGaN/GaN layers which absorb electrons from channels and virtual gate effects [ 12 ] which deplete the channel in the device by the accumulated negative charges in the surface have been found to be the main reason causing the reduction of 2DEG in channels [ 16 ].…”

Characterization of high-frequency noise performance of GaN double heterojunction HEMT

“…Until now, research effects, including modeling of noise, improvement of process, and advanced epitaxial layer structure, have been reported to improve the microwave performance of GaN-based HEMT [7][8][9][10]. GaN double heterojuction HEMT (DH-HEMT) has been studied in the application of high output power devices [11][12][13][14].…”