High Thermal Dissipation of Normally off p-GaN Gate AlGaN/GaN HEMTs on 6-Inch N-Doped Low-Resistivity SiC Substrate

Abstract

Efficient heat removal through the substrate is required in high-power operation of AlGaN/GaN high-electron-mobility transistors (HEMTs). Thus, a SiC substrate was used due to its popularity. This article reports the electrical characteristics of normally off p-GaN gate AlGaN/GaN high-electron-mobility transistors (HEMTs) on a low-resistivity SiC substrate compared with the traditional Si substrate. The p-GaN HEMTs on the SiC substrate possess several advantages, including electrical characteristics and good qualities of epitaxial crystals, especially on temperature performance. Additionally, the price of the low-resistivity SiC substrate is three times lower than the ordinary SiC substrate.

Keywords: low-resistance SiC substrate; normally off; p-GaN gate HEMT; temperature.

Figure 1

(a) Structure of p-GaN gate HEMT on low-resistance substrate. (b) Outward appearance of low-resistance SiC wafer.

Figure 2

I–V characteristics of LRSiC-HEMT and Si-HEMT with L_GS/L_G/L_GD/W_G = 2/5/5/100 μm. (a) Transfer I_DS-V_GS characteristic. (b) Output I_DS-V_DS characteristic.

Figure 3

(a) Off-state breakdown voltage and (b) vertical breakdown voltage measurement.

Figure 4

Temperature following the time, with the device operating for 60 s and cooling down for 50 s.

Figure 5

(a) Transfer characteristics of LRSiC-HEMT from 25 to 175 °C; (b) T-dependence of V_TH and R_ON.

Figure 6

Pulsed I_DS−V_DS characteristics from quiescent gate bias (V_GSQ) point of 0 V with 2 µs pulse width and 200 µs pulse period. The quiescent drain bias (V_DSQ) was then swept from 0 to 80 V (in 20-V increments).

Figure 7

Dynamic R_on ratio of LRSiC-HEMT and Si-HEMT.