Integration of Oxidized Silicon- and Hydrogen- Terminated Diamond p-Channels for Normally-Off High-Voltage Diamond Power Devices
Yu Fu, Zeyang Ren, Kai Su, Jinfeng Zhang, Ruowei Liu, Yijiang Li, Liaoliang Zhu, Jintao Meng, Peng Qian, Dong Wang, Yue Hao, Hiroshi Kawarada, Jincheng Zhang
Abstract
With a dense two-dimensional hole gas (2DHG) p-type conductive layer near the surface, hydrogen-terminated (C–H) diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) have shown typical normally-on operations and high breakdown voltages (VBR). Owing to the high MOS interface quality, the oxidized silicon-terminated (C–Si–O) diamond MOSFETs have featured excellent normally-off characteristics, such as high threshold voltage (VTH). However, the reported C–Si–O diamond MOSFETs were all exhibited an overlapping-gate structure, and therefore couldn’t withstand high voltages. In this work, we demonstrated a novel C–H diamond MOSFET structure with a partial C–Si–O channel to improve the voltage withstand capability of normally-off C–Si–O diamond MOSFETs. The C–H/C–Si–O/C–H channel structure was achieved by forming an entire C–Si–O channel first, and then selectively replacing the C–Si–O channel to the C–H channel by using a SiO2mask. As a result, for the fabricated device with a C–Si–O channel length of 2 μm and a gate-to-drain distance (LGD) of 11 μm,VTH= -8.6 V and OFF-stateVBR= -1376 V have been obtained. These competitive results reveal that the proposed device structure is promising in pushing the normally-off C–Si–O diamond MOSFETs into the high voltage applications.