MIS-Based GaN Schottky Barrier Diodes: Interfacial Conditions on the Reverse and Forward Properties

In this work, we have conducted systematic studies on the interfacial conditions for gallium nitride (GaN)-based trench metal/insulator/semiconductor (MIS)-type barrier Schottky rectifier (TMBS) with the help of the T-CAD tools. Our results show that the donor-type traps tend to reduce the Schottky barrier height ( ${q}\varphi _{s}$ ), which weakens the charge coupling effect, increases the leakage current, and finally reduces the breakdown voltage (BV). On the contrary, the acceptor-type traps at the contact interface and mesa sidewall will increase ${q}\varphi _{s}$ and the turn-on voltage ( ${V}_{\mathrm{ON}}$ ) because they can capture electrons in the mesa region and show the negative polarity. This then enhances the electron depletion at the contact interface and the mesa sidewall, resulting in an increase in ${q}\varphi _{s}$ and ${V}_{\mathrm{ON}}$ . Therefore, this process can increase the reverse blocking characteristics. However, for solving the complicated interfacial conditions in the Schottky contact region, we propose using an MIS structure with a 1-nm Al2O3 insulation layer for the GaN-based TMBS rectifiers. Based on the results, the tunneling process and thermionic-emission (TE) process take into account for the current transport mechanism for the MIS-TMBS rectifiers. Meanwhile, the 1-nm thick Al2O3 interlayer increases the effective Schottky barrier height ( ${q}\varphi _{s} + {q}\varphi _{T}$ ), which significantly reduces the reverse leakage. In addition, this design offers more freedom in selecting the Schottky contact electrode for the MIS-TMBS rectifier.