A new planar MISHEMT structure is proposed with the drain surrounded (D-S) by the gate channel. The gate channel serves as the stop-ring of the drain voltage, eliminating the damages from the high voltage on the mesa edge and isolation area. As a result, the leakage of the D-S MISHEMT is found to be reduced by almost 3 orders comparing with the source surrounded (S-S) MISHEMT. A saturated output current density of 740 mA/mm and an ON-resistance of 13.09 Ω-mm are obtained for device with LG/LGS/LGD/WC = 1.5/5/20/250 μm. Meanwhile, the degradation of dynamic ON-resistance and off-state breakdown performance are investigated in both D-S and S-S MISHEMT, which indicates excellent reliability of the D-S MISHEMT.
Experimental and simulation I–V characteristics of the cap gate high electron mobility transistor (HEMT) are reported. The two-dimensional simulations results are in conformity with the realistic HEMT perfectly, indicating reliable and acceptable of the TCAD simulation method in GaN-based devices. Depending on this, further researches on the cap gate HEMT are carried out by TCAD software, which analyzes the impact of recessed depth of gate barrier, the dimension of LG and cap gate structure on GaN HEMT performances.
A novel E-mode AlGaN/GaN HEMT with double-doped p-gate (DDP) is proposed to improve output current and verified by TCAD simulation. The heavily p-doped region of the AlGaN gate layer ensures enhancement-mode (E-mode) operation and the lightly p-doped region of the AlGaN gate layer reduces the channel resistance. The simulated results have demonstrated that DDP HEMT delivers a much larger maximum drain current (IMAX = 334 mA/mm) than the conventional p-gate (CP) HEMT (IMAX = 144 mA/mm) while maintaining a high threshold voltage (VTH ~1.5 V). The simulated results also indicate that the DDP gate structure could decrease the peak electric field (EC) and thus improve the reliability of the device under off-state high-drain-bias (HDBT).