Electron beam induced damage of silicon germanium

The effect of electron beam irradiation damage to pseudomorphic modulation-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 significantly altered, For 300 keV irradiated electrons, the resistivity of the material increased as the dose of electrons was increased. For 100 keV and higher electron irradiation energies, the material became more resistive as the irradiation energy was increased. The 2DHG material became highly resistive at low temperatures and froze out at between 20 and 30 K. Annealing at 400 degrees C to 500 degrees C on 40 keV samples with 2 C/m(2) doses could return the resistivity of the material at 300 K to the non-irradiated value, but the large increase in resistivity for annealing, temperatures above 500 degrees C suggests that the irradiation produced a significant number of defects which accelerated the relaxation of the strained Si0.87Ge0.13 channel by thermal processing. A number of narrow channel devices were fabricated in high mobility modulation-doped Si/SiGe two dimensional electron gas material and investigated at 4.2 K using the electron beam irradiation to locally damage material into an insulting state. Fluctuations were found in a number of devices with patterned widths below 0.5 mu m. (C) 1996 American Vacuum Society