Field-induced Acceptor Ionization in Enhancement-mode GaN p-MOSFETs

This work demonstrates a p-MOSFET with a GaNM.l_0.2Ga_0.8N (20 nm)/GaN heterostructure grown by metal-organic-chemical vapor deposition (MOCVD) on 6-inch Si substrate with optimized self-aligned process. Devices with source-to-drain distance, L_SD, varying from 1 μm down to 200 nm were fabricated. Significant field-induced acceptor ionization was found in these devices at high drain voltages. The device with L_SD=200 nm shows a record combination of I_ON of ~45 mA/mm and ON-OFF ratio of ~10⁴ when compared with other p-channel transistor demonstrations. The device also exhibits Enhancement-mode operation with threshold voltage of -0.5V. The best device shows an ON-current of 100 mA/mm but at the expense of lower on-off ratio of ~10².