Doped multichannel AlAs0.56Sb0.44/In0.53Ga0.47As field effect transistors

A depletion-mode doped-channel field effect transistor (DCFET) using an AlA s0.56Sb0.44/In0.53Ga0.47As heterostructure with multiple channels and a gat e-length of 1.0 mu m is presented. The device structure is grown by molecul ar beam epitaxy and consists of three doped In0.53Ga0.47As channels separat ed by undoped AlAs0.56Sb0.44 layers. A zero gate-bias saturation current de nsity of 350mA/mm, extrinsic transconductance as high as 250mS/mm, a unity current gain cutoff frequency of 18GHz, and a maximum oscillation frequency of 60GHz are reported. This multiple channel approach results in wide line arity of the DC and RF performances of the device.