RTA removal of E-beam-induced damage in GaAs-AlGaAs heterostructures as determined by magnetotransport characterization

Abstract

Measurement was made of the effect of electron energy on the 2D EG transport properties of high electron mobility transistor (HEMT) structures at low temperatures. The structures were grown by molecular beam epitaxy (MBE) with a 2D EG approximately 850A below the surface. A Cambridge EBMF 10.5 was used for electron irradiation with electron energies between 2.5 and 20 keV. The HEMTs were fabricated into Hall bars, and damage was assessed by changes in the 2D EG concentrations as determined from Shubnikov-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. The effect of performing RTA on all samples simultaneously at 450° C for 30 sec was to remove damage and in some cases restore the sample to its original mobility.