THE IMPACT OF LATTICE DILATION ON DEEP STATES IN MBE GAAS

Deep level transient spectroscopy (DLTS) of n-type, molecular beam epi taxially grown GaAs has revealed a large increase in the concentration s of the characteristic deep electron traps, known as M states, with e rbium doping. Total M trap concentrations in excess of 5 X 10(15) cm-3 are measured for a moderate erbium doping level of 1 X 10(18) cm-3 . These high M trap concentrations can be increased by a further two ord ers of magnitude by growth upon strained, more heavily erbium-doped ma terial. Dilation of the GaAs matrix, arising in this case from the pre sence of the large Erbium atoms and ErAs precipitates in the lattice, is believed to play a major role in the creation of these characterist ic MBE defects.