H. Hier

Kink effect in submicrometer-gate MBE-grown InAlAs/InGaAs/InAlAs heterojunction MESFETs

The authors report the influence of the kink effect on the DC and microwave performance of i-InAlAs heterojunction doped-channel MESFETs lattice matched to an InP substrate with submicrometer gates. Kink effects were observed at room temperature as well as at 77 K in the DC measurement. The kinks seem to be related to deep-level electron trapping, and are not present at microwave frequencies. Measured results are presented showing that the existence of kinks at low operating frequencies does not seem to degrade the microwave performance of the devices.<<ETX>>

High-performance InAlAs/InGaAs HEMTs and MESFETs

The fabrication and microwave performance of heterostructure InAlAs/InGaAs HEMTs (high-electron-mobility transistors) and MESFETs are described. Maximum stable gains of 14.3 dB for a HEMT and 12 dB for a MESFET at 26.5 GHz have been achieved. These are believed to be record gains for FETs having gates as long as 0.7 mu m.<<ETX>>

DC and RF characteristics of doped multichannel AlAs/sub 0.56/Sb/sub 0.44//In/sub 0.53/Ga/sub 0.47/As field effect transistors with variable gate-lengths

Depletion-mode doped-channel field effect transistors (DCFETs) using a AlAs/sub 0.56/Sb/sub 0.44//In/sub 0.53/Ga/sub 0.47/As heterostructure with multiple channels grown by molecular beam epitaxy (MBE) on an InP substrate are presented. Devices with gate lengths ranging from 0.2 /spl mu/m to 1.0 /spl mu/m have been fabricated. Three doped In/sub 0.53/Ga/sub 0.47/As channels separated by undoped AlAs/sub 0.56/Sb/sub 0.44/ layers are used for the devices. The devices exhibit unity current gain cut-off frequencies typically between 18 GHz and 73 GHz and corresponding maximum oscillation frequencies typically between 60 GHz and 160 GHz. The multiple channel approach results in wide linearity of dc and RF performance of the device.

Growth and fabrication of InGaAs/InAlAs HEMTs on bonded-and-etch-back InP-on-Si

InGaAs/InAlAs HEMTs fabricated on bonded-and-etched-back InP-on-Si substrates are reported. The process involves depositing SiO/sub 2/ on both the Si and InP substrates. The wafers are then contacted and bonded in a furnace at low temperature. Defects in the bond can be minimized by bonding in a particle-free environment. After bonding to a Si substrate, the InP wafer is thinned to <10 mu m and a strain-relief grid is etched through the InP to the SiO/sub 2/ layer. For fabrication of the HEMT, a standard processing sequence of mesa isolation, ohmic-contacts formation, gate-metal deposition and overlay was used. A maximum transconductance of 180 mS/mm was measured for a 1.2- mu m-gate-length device.<<ETX>>

High-current, planar-doped pseudomorphic hemts Ga0.4In0.6As/Al0.48In0.52As HEMTs

The letter reports the first successful growth and fabrication of high-performance, planar-doped pseudomorphic GaInAs/AlInAs HEMTs. Hall mobilities as high as 11900cm2/Vs (300 K) with sheet-electron concentrations of 2.4 × 1012cm−2 were measured for the heterostructures. A drain-saturation current of 1 A/mm, a transconductance of 420mS/mm, and an extrapolated f1 of 64 GHz were achieved in a 0.5 μm gate-length HEMT.