The T-gate stem height of In Al As/In Ga As In P-based high electron mobility transistor(HEMT) is increased from165 nm to 250 nm. The influences of increasing the gate stem height on the direct current(DC) and radio f...The T-gate stem height of In Al As/In Ga As In P-based high electron mobility transistor(HEMT) is increased from165 nm to 250 nm. The influences of increasing the gate stem height on the direct current(DC) and radio frequency(RF)performances of device are investigated. A 120-nm-long gate, 250-nm-high gate stem device exhibits a higher threshold voltage(Vth) of 60 m V than a 120-nm-long gate devices with a short gate stem, caused by more Pt distributions on the gate foot edges of the high Ti/Pt/Au gate. The Pt distribution in Schottky contact metal is found to increase with the gate stem height or the gate length increasing, and thus enhancing the Schottky barrier height and expanding the gate length,which can be due to the increased internal tensile stress of Pt. The more Pt distributions for the high gate stem device also lead to more obvious Pt sinking, which reduces the distance between the gate and the In Ga As channel so that the transconductance(gm) of the high gate stem device is 70 m S/mm larger than that of the short stem device. As for the RF performances,the gate extrinsic parasitic capacitance decreases and the intrinsic transconductance increases after the gate stem height has been increased, so the RF performances of device are obviously improved. The high gate stem device yields a maximum ft of 270 GHz and fmax of 460 GHz, while the short gate stem device has a maximum ft of 240 GHz and the fmax of 370 GHz.展开更多
1.0μm gate-length GaAs-based MHEMTs have been fabricated by MBE epitaxial material and contact-mode lithography technology. Pt/Ti/Pt/Au and Ti/Pt/Au were evaporated to form gate metals. Excellent DC and RF performanc...1.0μm gate-length GaAs-based MHEMTs have been fabricated by MBE epitaxial material and contact-mode lithography technology. Pt/Ti/Pt/Au and Ti/Pt/Au were evaporated to form gate metals. Excellent DC and RF performances have been obtained, and the transconductance, maximum saturation drain current density, threshold voltage, current cut-off frequency,and maximum oscillation frequency of Pt/Ti/Pt/Au and Ti/Pt/Au MHEMTs were 502 （503） mS/mm, 382（530）mA/mm,0.1（ - 0.5）V,13.4（14.8）GHz,and 17.0（17.5）GHz,respectively. DC-10GHz single-pole double-throw （SPDT） switch MMICs have been designed and fabricated by Ti/Pt/Au MHEMTs. Insertion loss,isolation,input,and out- put return losses of SPDT chips were better than 2.93,23.34,and 20dB.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61434006)。
文摘The T-gate stem height of In Al As/In Ga As In P-based high electron mobility transistor(HEMT) is increased from165 nm to 250 nm. The influences of increasing the gate stem height on the direct current(DC) and radio frequency(RF)performances of device are investigated. A 120-nm-long gate, 250-nm-high gate stem device exhibits a higher threshold voltage(Vth) of 60 m V than a 120-nm-long gate devices with a short gate stem, caused by more Pt distributions on the gate foot edges of the high Ti/Pt/Au gate. The Pt distribution in Schottky contact metal is found to increase with the gate stem height or the gate length increasing, and thus enhancing the Schottky barrier height and expanding the gate length,which can be due to the increased internal tensile stress of Pt. The more Pt distributions for the high gate stem device also lead to more obvious Pt sinking, which reduces the distance between the gate and the In Ga As channel so that the transconductance(gm) of the high gate stem device is 70 m S/mm larger than that of the short stem device. As for the RF performances,the gate extrinsic parasitic capacitance decreases and the intrinsic transconductance increases after the gate stem height has been increased, so the RF performances of device are obviously improved. The high gate stem device yields a maximum ft of 270 GHz and fmax of 460 GHz, while the short gate stem device has a maximum ft of 240 GHz and the fmax of 370 GHz.
文摘1.0μm gate-length GaAs-based MHEMTs have been fabricated by MBE epitaxial material and contact-mode lithography technology. Pt/Ti/Pt/Au and Ti/Pt/Au were evaporated to form gate metals. Excellent DC and RF performances have been obtained, and the transconductance, maximum saturation drain current density, threshold voltage, current cut-off frequency,and maximum oscillation frequency of Pt/Ti/Pt/Au and Ti/Pt/Au MHEMTs were 502 （503） mS/mm, 382（530）mA/mm,0.1（ - 0.5）V,13.4（14.8）GHz,and 17.0（17.5）GHz,respectively. DC-10GHz single-pole double-throw （SPDT） switch MMICs have been designed and fabricated by Ti/Pt/Au MHEMTs. Insertion loss,isolation,input,and out- put return losses of SPDT chips were better than 2.93,23.34,and 20dB.
