Structural and photoluminescence studies of Er implanted Be doped and undoped low-temperature grown GaAs

Characteristic 1.54 mu m Er3+ emission has been observed from Er-implanted and annealed, low-temperature grown GaAs Be doped and undoped samples. Er p lateau implantations (480, 155, and 40 keV successive implants) were perfor med at 300 degrees C covering calculated Er concentrations from 10(18) up t o 10(20) Er/cm(3). Cross-sectional transmission electron microscopy studies reveal very little structural damage for these elevated temperature implan ts up to an Er total fluence of 1.36 X 10(14) Er/cm(2). No Er emission was observed from any of the as-implanted samples but it was observed after pos timplantation annealings at 650 and 750 degrees C temperatures. The Er emis sion was significantly more intense after 650 degrees C anneals, for Be dop ed samples, and after 750 degrees C anneals for undoped samples. It appears on top of a broad background luminescence associated with midgap states. T he Er emission intensity was found to scale linearly with the total Er impl antation fluence up to Er concentration of similar to 10(19) Er/cm(3). Er p recipitation was observed after 750 degrees C annealing for 10(19) Er/cm(3) samples, but could be observed for 10(20) Er/cm(3) Er-doped samples even a fter a 650 degrees C anneal. These precipitates are most likely ErAs. (C) 1 999 American Institute of Physics. [S0021-8979(99)07402-2].