Remarkable Reduction in IG with an Explicit Investigation of the Leakage Conduction Mechanisms in a Dual Surface-Modified Al2O3/SiO2 Stack Layer AlGaN/GaN MOS-HEMT

We demonstrated the performance of an Al2O3/SiO2 stack layer AlGaN/GaN metal-oxide semiconductor (MOS) high-electron-mobility transistor (HEMT) combined with a dual surface treatment that used tetramethylammonium hydroxide (TMAH) and hydrochloric acid (HCl) with post-gate annealing (PGA) modulation at 400 ?degrees C for 10 min. A remarkable reduction in the reverse gate leakage current (I-G) up to 1.5x10(-12) A/mm (@ V-G = -12 V) was observed in the stack layer MOS-HEMT due to the combined treatment. The performance of the dual surface-treated MOS-HEMT was significantly improved, particularly in terms of hysteresis, gate leakage, and subthreshold characteristics, with optimized gate annealing treatment. In addition, an organized gate leakage conduction mechanism in the AlGaN/GaN MOS-HEMT with the Al2O3/SiO2 stack gate dielectric layer was investigated before and after gate annealing treatment and compared with the conventional Schottky gate. The conduction mechanism in the reverse gate bias was Poole-Frankel emission for the Schottky-gate HEMT and the MOS-HEMT before annealing. The dominant conduction mechanism was ohmic/Poole-Frankel at low/medium forward bias. Meanwhile, gate leakage was governed by the hopping conduction mechanism in the MOS-HEMT without gate annealing modulation at a higher forward bias. After post-gate annealing (PGA) treatment, however, the leakage conduction mechanism was dominated by trap-assisted tunneling at the low to medium forward bias region and by Fowler-Nordheim tunneling at the higher forward bias region. Moreover, a decent product of maximum oscillation frequency and gate length (f(max) x L-G) was found to reach 27.16 GHz.mu m for the stack layer MOS-HEMT with PGA modulation. The dual surface-treated Al2O3/SiO2 stack layer MOS-HEMT with PGA modulation exhibited decent performance with an I-DMAX of 720 mA/mm, a peak extrinsic transconductance (G(MMAX)) of 120 mS/mm, a threshold voltage (V-TH) of -4.8 V, a higher I-ON/I-OFF ratio of approximately 1.2x109, a subthreshold swing of 82 mV/dec, and a cutoff frequency(f(t))/maximum frequency of (f(max)) of 7.5/13.58 GHz.

Automated summary

The study demonstrated the performance of an Al2O3/SiO2 stack layer AlGaN/GaN metal-oxide semiconductor high-electron-mobility transistor with a dual surface treatment using TMAH and HCl, along with post-gate annealing modulation. The dual surface-treated MOS-HEMT showed significant improvements in hysteresis, gate leakage, and subthreshold characteristics by optimizing gate annealing treatment.