Modification of transconductance characteristics for ion-implanted GaAs/AlGaAs heterojunction MESFETs |
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Authors: | Wang GW Feng M Liaw YP Kaliski R Lau CL Ito C |
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Affiliation: | Ford Microelectron. Inc., Colorado Springs, CO, USA; |
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Abstract: | Inverted GaAs/AlGaAs heterostructures grown by MOCVD have been used to fabricate conventional ion-implanted MESFETs. Two types of GaAs/AlGaAs heterojunctions are studied. One type has a compositionally graded AlGaAs layer which provides a built-in field and corresponding quantum well at the heterointerface. The other type has a constant-composition AlGaAs layer. 0.5 mu m gate devices fabricated using the ungraded AlGaAs layer show a maximum extrinsic transconductance G/sub m/ of 280 mS/mm and a small G/sub m/ variation over a gate voltage range of 1.5 V. In comparison, devices fabricated using the graded AlGaAs layer exhibit higher transconductance over all the gate voltages and an enhancement of G/sub m/ up to 420 mS/mm at low gate bias.<> |
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