ELEVATED-TEMPERATURE 3-MEV SI AND 150-KEV GE IMPLANTS IN INP-FE

Variable-fluence 3-MeV Si+ and 150-keV Ge+ implants were performed into InP:Fe at 200-degrees-C. Lattice damage in the material is greatly reduced over comparable room-temperature (RT) implantations and is rather insensitive to fluence for Si+ implantation in the range of 8 x 10(14)-5 x 10(15) cm-2, and no amorphization occurs. For 8 x 10(14)-cm-2 Si+ implantation at 200-degrees-C, the dopant activation is 82% and carrier mobility is 1200 cm2/V s after 875-degrees-C/10-s annealing, whereas for the RT implantation the corresponding values are 48% and 765 cm2/V s, respectively. The reasons for the improved mobility in the elevated-temperature implants were investigated using Rutherford-backscattering spectrometry. At a dose of 8 x 10(14) cm-2, the aligned yield after annealing is close to that of a virgin sample, indicating a low concentration of residual damage in the 200-degrees-C implant, whereas the lattice remained highly defective in the RT implanted sample. Elevated-temperature implantation of Si+ and Pi+ ions was also investigated. Coimplantation did yield an improvement in activation for an implanted fluence of 2 x 10(15) cm-2 Si+, but resulted in an inferior lattice quality which degraded the carrier mobility compared to a Si+ (only) implant. For a 1 x 10(14)-cm-2 Ge+ implant, the maximum dopant activation is 50% (donor) and the material did not turn p type even after 925-degrees-C annealing.