Performance enhancement in a metal-insulator-semiconductor-like pseudomorphic transistor by utilizing an n^--GaAs/n⁺-In_0.2Ga_0.8As two-layer structure

A high performance metal-insulator-semiconductor-like pseudomorphic field-effect transistor utilizing an n^--GaAs/n⁺-In_0.2Ga_0.8As two-layer structure was fabricated and demonstrated. The n^--GaAs layer is used as the Schottky contact layer whereas the n⁺-In_0.2Ga_0.8As quantum well is employed as the active channel. Due to the excellent properties of the InGaAs layer and carrier confinement effect at the In_0.2Ga_0.8As-GaAs heterointerface, the device under study shows the advantages of high breakdown voltage, high current capability, very large gate voltage swing for high transconductance operation, and ease of fabrication. For a 2×100 μm² gate device, a breakdown voltage of 17.4 V, a maximum drain saturation current of 930 mA/mm, a maximum extrinsic transconductance of 230 mS/mm, and a very wide gate voltage range larger than 3 V with the extrinsic transconductance higher than 200 mS/mm are obtained. Therefore, the device has great potential for use in high speed, high power, and large input signal circuit applications.