terça-feira, 25 de agosto de 2015
Advanced GaN-based MISFET for RF/Power Application KI SIK IM - KYUNGPOOK NATIONAL UNIVERSITY
( Abstract ) the advanced GaN-based MISFETs for RF/power application were fabricated and characterized using advanced technologies. The applications of the GaN-based MISFET are the RF amplifier in chapter 3 and power switching in chapter 4 and 5, respectively. The key requirements of HEMT are high frequency, high RF power, and low leakage current. AlGaN/GaN HEMT with T-gate of 0.15 ?m exhibits excellent performances such as Id,max of 1 A/mm, maximum gm of 180 mS/mm, fT of 55 GHz, and fmax of 100 GHz with Pout = 4 W/mm. Appling the air-bridge process, AlGaN/GaN HEMT with 30-finger for applying K-band amplifier was successfully fabricated without reducing DC & RF performance. Normally-off operation, low on-resistance, and high breakdown voltage are very important for power switching application. A recessed-gate normally-off GaN MOSFET with an Al2O3 gate insulator was proposed by utilizing an extremely high 2-D electron-gas density (> 1014/cm2) at an AlGaN/GaN heterostructure as source and drain, which can be obtained by controlling the tensile stress accompanied with the growth of GaN on silicon substrate. The fabricated MOSFET with stress controlled source and drain exhibited excellent device performances, such as a threshold voltage of 2 V, drain current of 353 mA/mm, extrinsic gm of 98 mS/mm, and ?FE of 225 cm2/V?s. The dry etching condition of AlGaN layer for recessed-gate was optimized to obtaining the high Vth (> 2 V).