Influence of Terminal Field Plate on Breakdown Voltage in GaN-Based Schottky Barrier Diode

Abstract

In order to improve the breakdown voltage of the Schottky barrier diode(SBD), a GaN-based SBD with a field plate(FP) structure has been systematically studied. Based on the Silvaco TCAD software, and by the method of controlling variables, that is, in some conditions of the different field plate length( L_(FP)), insulating layer thickness(T_(FP)), and the doping concentration(N_D) in the GaN drift region, the differences of the device breakdown voltage(BV)have been simulated. Also, the change trend of the BV has been confirmed by the surface electric field distribution of the device. The results are the followings: When T_(FP)= 0.3 μm, N_D=1 × 10~(16) cm~(-3), and L_(FP)increases from 0 to 2.0 μm,the BV of SBD has gradually increased and reached the threshold when L_(FP)= 1.6 μm. When L_(FP)= 1.6 μm, N_D= 1 ×10~(16) cm~(-3), and the change of T_(FP)from 0.1 μm to 0.4 μm, the BV has firstly increased and then decreased, and reached the maximum value when T_(FP)= 0.3 μm. When L_(FP)= 1.6 μm, T_(FP)= 0.3 μm, and N_Dincreases from 1 × 10~(16) cm~(-3) to 1 × 10~(19) cm~(-3), the BV has only gradually decreased. Compared with the traditional field-free GaN-SBD, the BV of the designed terminal field-plate GaN-SBD can reach 840 V with the conditions of L_(FP)= 1.6 μm, T_(FP)= 0.3 μm, N_D=1 × 10~(16) cm~(-3). It is further confirmed that the proposed FP can extend to the depletion region under the anode, resulting in alleviating the current crowding around the anode corner.

Keywords

• field plate structure
• gan
• schottky barrier diode
• breakdown voltage