Theoretical and Experimental Study on AlGaN/GaN Schottky Barrier Diode on Si Substrate with Double-Heterojunction

An AlGaN/GaN Schottky barrier diode (SBD) with double-heterojunction is theoretically and experimentally investigated on the GaN/AlGaN/GaN/Si-sub. The two-dimensional hole gas (2DHG) and electron gas (2DEG) are formed at the GaN-top/AlGaN and AlGaN/GaN interface, respectively. At the off-state, the 2DEH and 2DHG are partially depleted and then completely disappear. There remain the fixed positive and negative polarization charges, forming the polarization junction. Therefore, a flat electric field in the drift region and a high breakdown voltage (BV) are obtained. Moreover, the anode is recessed to reduce turn-on voltage (V_ON). The low-damage ICP etching process results in the improved Schottky contacts, and a low leakgae current and a low V_ON is obtained. The fabricated SBD exhibits a BV of 1109 V with anode-to-cathode distance (L_AC) of 11 μm. The fabricated SBDs achieve a low V_ON of 0.68 V with good uniformity, a high on/off current ratio ∼ 10¹⁰ at room temperature, a low specific on-resistance (R_ON,SP) of 1.17 mΩ cm², and a high Baliga's figure-of-merit (FOM) of 1051 MW/cm².