| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 538947 | Microelectronic Engineering | 2015 | 6 Pages |
•Grading Al composition of barrier layer alleviates the impact of piezoelectric polarization on 2-DEG.•Adjusting Al-composition of AlyGa1−yN cap-layer and p-doping concentration on GaN buffer-layer enhances HEMT's drain-current.
We propose a novel, normally-off AlGaN/GaN high-electron-mobility transistor (HEMT) governed by polarization engineering. The fundamental concept is to grade the Al composition of the barrier layer from GaN to AlxGa1−xN, thereby alleviating the impact of piezoelectric polarization on the two-dimensional electron gas (2-DEG) and establishing a conduction-band profile well above the Fermi energy. These effects lead to a positive shift in the threshold voltage of the device and benefit the normally-off operation. It is observed that the device’s DC transfer characteristics can be further modulated simply by adjusting the Al composition of the AlyGa1−yN cap layer and the p-type doping concentration at the top of the GaN buffer layer. These findings, based on a physical simulation of the proposed device, provide a guideline for the implementation of highly efficient, normally-off AlGaN/GaN HEMTs.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide
