An Ultralow Turn-On GaN Lateral Field-Effect Rectifier With Schottky-MIS Cascode Anode

In this article, we experimentally propose an ultralow turn-on GaN lateral field-effect rectifier (LFER) incorporating a Schottky-MIS cascode anode (CA-LFER). In the CA-LFER, the lateral Ti/GaN Schottky contact as well as the Ti/HfO2/AlGaN MIS-controlled channel is cascoded at the anode. Ti, which has a very low work function, contributes to lowering the Schottky barrier height (SBH) at the lateral Ti/GaN Schottky contact. At the same time, both Ti and the high dielectric constant HfO2 material can significantly lower the threshold voltage ( ${V}_{\text {TH}}$ ) of the Ti/HfO2/AlGaN MIS-controlled channel. The two features result in an ultralow turn-on voltage ( ${V}_{\text {ON}}$ ). Furthermore, when applying a reverse bias, the potential difference between the Ti anode metal and the two-dimensional electron gas (2DEG) in the GaN channel immediately depletes the Ti/HfO2/AlGaN MIS-controlled channel. As a result, the low SBH lateral Ti/GaN Schottky contact can be protected from the high reverse leakage current ( ${I}_{\text {LEAK}}$ ), leading to a high breakdown voltage (BV). The fabricated CA-LFER shows a competitive ${V}_{\text {ON}}$ – ${I}_{\text {LEAK}}$ relationship including an ultralow ${V}_{\text {ON}}$ of 0.19 V and a relatively low ${I}_{\text {LEAK}}$ of $3.6\times 10^{-{6}}$ A/mm, together with a BV of 710 V. This high performance suggests that the CA-LFER can be a promising candidate for the GaN power rectifier applications requiring ultralow ${V}_{\text {ON}}$ and a better ${V}_{\text {ON}}$ – ${I}_{\text {LEAK}}$ tradeoff.