Depletion-mode and enhancement-mode InGaP/GaAs δ-HEMTs for low supply-voltage applications
Journal
Semiconductor Science and Technology
Journal Volume
17
Journal Issue
2
Pages
156-160
Date Issued
2002-02
Author(s)
Abstract
We demonstrate that a new high electron-mobility transistor (HEMT) structure, using an additional n-GaAs cap layer, simultaneously fabricates both the enhancement-mode and depletion-mode of δHEMTs on the same chip, thus implementing a direct-coupled field-effect transistor logic circuit. For δ-HEMTs which have a gate dimension of 1 × 100 μm2, the threshold voltage VT for the depletion-mode δ-HEMT is about -1.4 V, while the threshold voltage VT and the maximum applied gate-to-source voltage for the enhancement-mode δ-HEMT are about +0.5 V and +1.6 V, respectively. When VDS = 1.5 V, the output current ID and the gm transconductance are 200 (180) mA mm-1 and 160 (180) mS mm-1, respectively, for the depletion-mode (enhancement-mode) δ-HEMT. The ac characteristics have also been investigated. Furthermore, it is found that better inverter performances can be obtained by using a narrower gate width of the depletion-mode load with a higher supply voltage.
SDGs
Type
journal article