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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 μm to 1.0 μm 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.