In this article, we propose and investigate a GaN-based trench metal–insulator–semiconductor barrier Schottky rectifier with a beveled mesa and field plate (BM-TMBS). According to our study, the beveled mesa and field plate structures help to reduce the density of potential lines at the mesa corner and deplete the drift region in two-dimensional mode, respectively. By doing so, the electric field at the bottom corner of the trenches and Schottky contact/GaN interface can be decreased significantly and the breakdown voltage can also be improved remarkably when compared with the conventional TMBS rectifiers and the planar Schottky barrier diodes. Meanwhile, assisted by the beveled mesa structure, the improved current spreading effect and a better conductivity modulation can be obtained in the forward-conduction state. Our studies also show that the electric field profiles and charge-coupling effect can be influenced by the mesa angle, the insulating layer thickness (Tox), and the trench depth (Dtr). As a result, the optimized BM-TMBS rectifiers can obtain a high BV of ∼2 kV and a current density of ∼3 kA/cm2 at the forward bias of 2 V.
In this work, a hybrid trench MOS barrier Schottky diode (TMBS) structure is proposed to improve both the forward current density and the breakdown voltage (BV) by using TCAD simulation tools. The hybrid structure means that the conventional TMBS rectifier is combined with a p-NiO/n-GaN diode. This can modulate the lateral energy bands by removing the conduction band barriers for electrons. Thus, the improved current spreading effect and the better conductivity modulation can be obtained, leading to the increased current density. Meanwhile, the embedded p-type NiO layer can also help to reduce the electric field at Schottky contact interface and the edge of anode contact/p-NiO layer interface. Thus, the breakdown voltage can be improved remarkably. Moreover, a detailed optimization strategy for the hybrid TMBS is also analyzed by varying the p-NiO layer thickness (TNiO) and the lengths of the anode electrode that is covered on the p-NiO layer (LA).
We report a GaN-based Schottky barrier diode with a p-NiO field ring and field plate. It shows a low turn-on voltage (V
ON) of ∼0.6 V, an On-resistance (R
ON) of ∼6.5 mΩ·cm2, a nearly unity ideality factor of 1.13 at V
F = 0.3 V, and a high on/off current ratio of ∼1010. The breakdown voltage (BV) is increased from 300 to 1100 V, rendering a relatively high Baliga’s power figure-of-merit of ∼0.2 GW cm−2. The improved performance is attributed to the improved current spreading effect and the suppressed field crowding effect via the implemented p-NiO.
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