Ultra-thin barrier(UTB) 4-nm-Al Ga N/Ga N normally-off high electron mobility transistors(HEMTs) having a high current gain cut-off frequency( fT) are demonstrated by the stress-engineered compressive Si N trench tech...Ultra-thin barrier(UTB) 4-nm-Al Ga N/Ga N normally-off high electron mobility transistors(HEMTs) having a high current gain cut-off frequency( fT) are demonstrated by the stress-engineered compressive Si N trench technology.The compressive in-situ Si N guarantees the UTB-Al Ga N/Ga N heterostructure can operate a high electron density of1.27×1013 cm-2, a high uniform sheet resistance of 312.8 Ω/, but a negative threshold for the short-gate devices fabricated on it. With the lateral stress-engineering by full removing in-situ Si N in the 600-nm Si N trench, the short-gated(70 nm) devices obtain a threshold of 0.2 V, achieving the devices operating at enhancement-mode(E-mode). Meanwhile,the novel device also can operate a large current of 610 m A/mm and a high transconductance of 394 m S/mm for the Emode devices. Most of all, a high fT/fmax of 128 GHz/255 GHz is obtained, which is the highest value among the reported E-mode Al Ga N/Ga N HEMTs. Besides, being together with the 211 GHz/346 GHz of fT/fmax for the D-mode HEMTs fabricated on the same materials, this design of E/D-mode with the realization of fmax over 200 GHz in this work is the first one that can be used in Q-band mixed-signal application with further optimization. And the minimized processing difference between the E-and D-mode designs the addition of the Si N trench, will promise an enormous competitive advantage in the fabricating costs.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2020YFB1804902)the National Natural Science Foundation of China(Grant No.61904135)+1 种基金the China Postdoctoral Science Foundation(Grant Nos.2018M640957 and BX20200262)the Natural Science Foundation of Shaanxi Province,China(Grant No.2020JQ-316).
文摘Ultra-thin barrier(UTB) 4-nm-Al Ga N/Ga N normally-off high electron mobility transistors(HEMTs) having a high current gain cut-off frequency( fT) are demonstrated by the stress-engineered compressive Si N trench technology.The compressive in-situ Si N guarantees the UTB-Al Ga N/Ga N heterostructure can operate a high electron density of1.27×1013 cm-2, a high uniform sheet resistance of 312.8 Ω/, but a negative threshold for the short-gate devices fabricated on it. With the lateral stress-engineering by full removing in-situ Si N in the 600-nm Si N trench, the short-gated(70 nm) devices obtain a threshold of 0.2 V, achieving the devices operating at enhancement-mode(E-mode). Meanwhile,the novel device also can operate a large current of 610 m A/mm and a high transconductance of 394 m S/mm for the Emode devices. Most of all, a high fT/fmax of 128 GHz/255 GHz is obtained, which is the highest value among the reported E-mode Al Ga N/Ga N HEMTs. Besides, being together with the 211 GHz/346 GHz of fT/fmax for the D-mode HEMTs fabricated on the same materials, this design of E/D-mode with the realization of fmax over 200 GHz in this work is the first one that can be used in Q-band mixed-signal application with further optimization. And the minimized processing difference between the E-and D-mode designs the addition of the Si N trench, will promise an enormous competitive advantage in the fabricating costs.
