Selenium Ion Implanted GaAs MESFETs

Abstract

Schottky barrier gated FETs have been fabricated by selenium ion implantation at room temperature and 2CXFC into Cr-doped semi-insulating GaAs and into undoped epitaxial buffer layers. Dual dose and energy implants were investigated, the depth variation of carrier concentration and mobility in the implanted layers being determined by the differential Hall technique. Devices with the best microwave performance were produced on buffer layers implanted at room temperature with 5×10¹³ Se cm^-2 at 100 keV plus 7.5×10¹² Se cm^-2 at 800 keV. The noise figure and associated gain of these devices at 12.75 GHz were 2.2 dB and 6.6 dB, respectively. The transfer characteristics and d.c. parameter uniformity of devices produced on the two materials are compared for samples implanted at both temperatures investigated.