Enhanced microwave performance of ion-implanted MESFET with graded GaAs/AlGaAs heterojunctions |
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Authors: | Wang GW Feng M Liaw YP Kaliski R Chang Y Lau CL Ito C |
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Affiliation: | Ford Microelectron. Inc., Colorado Springs, CO, USA; |
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Abstract: | Ion-implanted MESFETs have been fabricated on an inverted GaAs/AlGaAs heterostructure. The aluminium concentration in the AlGaAs is graded from 0% at the substrate to 30% at the heterointerface. A maximum extrinsic transconductance of 410 mS/mm is achieved with 0.5 mu m gate devices. This heterojunction ion-implanted FET (HIFET) also exhibits enhanced microwave performance, especially at low drain current, when compared to conventional ion-implanted GaAs MESFETs. At 20% of I/sub dss/, the current gain cutoff frequency f/sub t/ is 40 GHz, which increases up to a maximum value of 47 GHz as the drain current rises. These characteristics of high f/sub t/ and high gain at low current are advantageous for low-noise applications.<> |
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