Electron-beam-induced damage study in GaAs-AlGaAs heterostructures as determined by magnetotransport characterization

The effect of electron energy on the two-dimensional electron gas (2D EG) transport properties of high-electron-mobility transistor (HEMT) structures at low temperatures is measured. The structures were grown by molecular beam epitaxy (MBE) with a 2D EG approximately 850 AA below the surface. The HEMTs were fabricated into Hall bars, and damage was assessed by changes in the 2D EG concentrations as determined from Schubnikov-de Haas oscillations and changes in the mobility as determined from the zero magnetic-field resistivity. For electron energies from 5.0 to 12.5 keV, the electron dose produced a degradation of the Hall mobility. No damage was observed for electron energies outside this range; this result is attributed to the penetration depth and damage distribution.>