High breakdown voltage Schottky rectifier fabricated on bulk n-GaN substrate

Department of Physics, Auburn University, AUO, Alabama, United States
Solid-State Electronics (Impact Factor: 1.5). 11/2006; 50(11-12):1744-1747. DOI: 10.1016/j.sse.2006.09.009


Vertical Schottky rectifiers have been fabricated on a free-standing n-GaN substrate. Circular Pt Schottky contacts with different diameters (50 μm, 150 μm and 300 μm) were prepared on the Ga-face and full backside ohmic contact was prepared on the N-face by using Ti/Al. The electron concentration of the substrate was as low as ∼7 × 1015 cm−3. Without epitaxial layer and edge termination scheme, the reverse breakdown voltages (VB) as high as 630 V and 600 V were achieved for 50 μm and 150 μm diameter rectifiers, respectively. For larger diameter (300 μm) rectifiers, VB dropped to 260 V. The forward turn-on voltage (VF) for the 50 μm diameter rectifiers was 1.2 V at the current density of 100 A/cm2, and the on-state resistance (Ron) was 2.2 mΩ cm2, producing a figure-of-merit (VB)2/Ron of 180 MW cm−2. At 10 V bias, forward currents of 0.5 A and 0.8 A were obtained for 150 μm and 300 μm diameter rectifiers, respectively. The devices exhibited an ultrafast reverse recovery characteristics, with the reverse recovery time shorter than 20 ns.

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    • "These values are comparable to those reported on GaN-based SBDs [4], [14], [15]. Fig. 4 shows R on versus breakdown voltage of the state-ofthe-art GaN, SiC, and AlGaN/GaN HEMT-based SBDs [2]–[5], [14], [16]. "
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