UC Santa Barbara

Room-temperature non-radiative recombination is studied at single dislocations in Ga0.5In0.5P quantum wells grown on metamorphic templates using cathodoluminescence and electron channeling contrast imaging. An analysis of the light emission intensity profiles around single dislocations reveals that the average recombination strength of a dislocation decreases by a factor of four and seven as a result of decreasing growth temperature of the GaInP quantum well from 725 to 675 and 625 °C, respectively. This reduction occurs despite little change in the diffusion length, precluding the prospect of inducing carrier localization by ordering and phase separation in GaInP at lower growth temperatures. These observations are rationalized by the premise that point defects or impurities are largely responsible for the recombination activity of dislocations, and the extent of decoration of the dislocation core decreases with temperature. Preliminary evidence for the impact of the Burgers vector is also presented. The lowest growth temperature, however, negatively impacts light emission away from dislocations. Carrier recombination in the bulk and at dislocations needs to be considered together for metamorphic devices, and this work can lead to new techniques to limit non-radiative recombination.