Studies and comparisons of a N+-InGaP/δ(P+)-InGaP/n-GaAs hetero-planar-doped structure to high-linearity microwave field-effect transistors

We report a promising N+-InGaP/delta (P+)-InGaP/n-GaAs hetero-planar-doped barrier, which is used to fabricate both high-breakdown and self-aligned T-gate (SAT-gate) field-effect transistors (FETs), The characteristics of the devices and comparisons with previous reports are discussed. The enhanced conduction- and valence-band offsets associated with the new hetero-planar doped barrier show high-breakdown behaviour. In addition, high selective etching between InGaP and GaAs layers together with an ohmic gate allows the fabrication of a SAT-gate with a reduced gate-length of 0.8 mum. In the case of a high-breakdown FET, the drain-source breakdown voltage is as high as 32 V, In addition to competitive direct-current (dc) performances, a reduced knee voltage and improved frequency performances are obtained in SAT-gate FETs. The available unity-current-gain and unity-power-gain frequencies are, respectively, 19.5 and 30 GHz achieved as a 0.6 mum gate is obtained by forming a 1 mum metal gate. Furthermore, all the measured SAT-gate FETs exhibit high-linearity and high-uniformity de and alternating-current performances.