Physical Model Development for Fabricating MIS-Anode-Based 1100 V AlGaN/GaN-Based Lateral Schottky Barrier Diodes Grown on Silicon Substrate with Low Leakage Current

Abstract

This work develops unique physical models for AlGaN/GaN-based Schottky barrier diodes (SBDs) grown on silicon (Si) substrates. The carrier transport and impact ionization processes are different from those of devices grown on sapphire substrates. Defects in the GaN epitaxial layer generate abundant leakage current and the impact ionization coefficients for the GaN layer shall be revised. The revised physical models are utilized to design SBDs with metal/Al₂O₃/GaN-based (MIS) Schottky contact. Both numerically calculated and experimentally measured results prove the benefits of the passivation effect by the Al₂O₃ thin layer. The increased effective energy barrier height suppresses the image-force-caused energy band-lowering effect. As a result, the reverse leakage current is reduced by 3 orders of magnitude when compared with the reference SBD. The revised physical models predict a ≈1100 V breakdown voltage (BV) for the MIS SBD with a specific ON-resistance (R_on,sp) of ≈3.98 mΩ cm², which numbers are consistent with measured results. The revised physical models are also able to precisely study the electrical stress reliability such that the MIS-based Schottky contact can significantly reduce the surface trapping effect for electrons. This is proven by experimentally observing that the MIS SBD presents much stabler R_on,sp and turn-on voltage (V_on) in different electrical-stress conditions.