Performance of AlGaInP/InGaAs enhancement/depletion-mode pseudomorphic doping-channel field-effect transistors

• AlGaInP/InGaAs enhancement/depletion-mode pseudomorphic DCFETs are demonstrated.
• It presents a relatively large ΔEc value at AlGaInP/InGaAs heterojunction.
• AlGaInP/InGaAs heterojunction provides a large barrier to prevent electron into gate.
• The studied devices exhibit broad gate voltage swing in transistor characteristics.
• A direct-coupled FET logic characteristic is obtained at a low supply voltage.

Direct current and direct-coupled FET logic (DCFL) characteristics of AlGaInP/InGaAs enhancement/depletion-mode pseudomorphic doping-channel field-effect transistors (DCFETs) are demonstrated by experimental results. After wet selectively etching process, the enhancement-mode pseudomorphic DCFET with single doping channel is formed. A large forward gate voltage up to +3 (2.6) V is observed for the depletion-mode (enhancement-mode) device for the presence of a relatively large conduction band discontinuity at Al0.15Ga0.35In0.5P/In0.1Ga0.9As heterojunction. In the depletion-mode device with double doping channels, the drain-to-source saturation voltage is only 0.5 V as the VGS is fixed at 0 V. A maximum extrinsic transconductance of 235 (274) mS/mm and a threshold voltage of −1.3 (+0.36) V are observed in the depletion-mode (enhancement-mode) device. Furthermore, the noise margins NMH and NML are of 0.108 V (0.534 V), and 0.390 V (0.417 V) at a supply voltage of 1.5 V (2.0 V) in the DCFL application.