Abstract
In the thesis, a Dual Metal Schottky Barrier Diode (SBD) was proposed and fabricated on silicon (111) substrate with a thick GaN buffer layer to decrease the substrate leakage current. Two kinds of metal were utilized to form the anode electrode. One is Titanium which has a lower work function, and the other is Nickel which has a higher work function. The low work function metal lowers Schottky barrier height, so when the device is operated at forward bias, the turn on voltage would be lower. That is, the dual metal SBD will have a higher forward current when biasing at the same voltage compared with the conventional one. When the device is operated at reverse bias, the location of the peak electric field always happens at the corner of the anode which is closer to the cathode. The implementation of high work function metal there would help reducing the leakage current significantly. The measured forward current density is 192.7 A/cm2 at 2V forward bias. The specific on-resistance is 5.27 mΩ•cm2. A very low reverse current density of 2.2×10-4 A/cm2 was measured at 200V reverse bias. The on-off current ratio is about 106. The best breakdown voltage is 1020V, resulting in a figure-of-merit (BV2/Ron) as high as 197 MV/cm2.