Sub-Threshold Characteristics of Laterlly Gated AlGaAs/InGaAs pHEMT Fabricated with Focused Ion Beam Implantation

Published

September 1, 1999

Author(s)

W. F. Tseng, David H. Monk

Abstract

We have used a focused ion beam (FIB) technique to fabricate laterally gated AlGaAs/InGaAs pseudomorphic high electron mobility transistors (pHEMTs), and have characterized them electrically. The FIB direct-write defines the current path. An ion dose of 12 x 10¹⁴ ions/cm² from a 25 keV Ga⁺ beam gives satisfactory electrical isolation. The fabricated transistors show typical field-effect transistor (FET) characteristics. For a properly adjusted n-AlGaAs layer, transfer characteristics (I_ds vs. V_g) in the sub-threshold region show gate leakage similar to that of metal-semiconductor FETs. For the thicker n-AlGaAs layer, the sub-threshold transfer characteristic shows additional conduction with sporadic current-spikes. We attribute the cause of sporadic current-spikes to deep donors or DX centers in the silicon-doped AlGaAs layer.

Citation

Materials Letters

Pub Type

Journals

Keywords

deep donor, DX center, focused ion beam (FIB), pseudomorphic high electron, mobility transistor (pHEMT)

Citation

Tseng, W. and Monk, D. (1999), Sub-Threshold Characteristics of Laterlly Gated AlGaAs/InGaAs pHEMT Fabricated with Focused Ion Beam Implantation, Materials Letters (Accessed October 27, 2025)