ELECTRON-BEAM-INDUCED DAMAGE OF SILICON-GERMANIUM

The effect of electron beam irradiation damage to pseudomorphic modula tion-doped SiGe two dimensional hole gas (2DHG) was investigated. For typical poly(methylmethacrylate) type processes with electron energies of 40 keV and doses of 2 C/m(2) the material properties were not sign ificantly altered, For 300 keV irradiated electrons, the resistivity o f the material increased as the dose of electrons was increased. For 1 00 keV and higher electron irradiation energies, the material became m ore resistive as the irradiation energy was increased. The 2DHG materi al became highly resistive at low temperatures and froze out at betwee n 20 and 30 K. Annealing at 400 degrees C to 500 degrees C on 40 keV s amples with 2 C/m(2) doses could return the resistivity of the materia l at 300 K to the non-irradiated value, but the large increase in resi stivity for annealing, temperatures above 500 degrees C suggests that the irradiation produced a significant number of defects which acceler ated the relaxation of the strained Si0.87Ge0.13 channel by thermal pr ocessing. A number of narrow channel devices were fabricated in high m obility modulation-doped Si/SiGe two dimensional electron gas material and investigated at 4.2 K using the electron beam irradiation to loca lly damage material into an insulting state. Fluctuations were found i n a number of devices with patterned widths below 0.5 mu m. (C) 1996 A merican Vacuum Society.