An RDS, LEED, and STM Study of MOCVD-Prepared Si (100) Surfaces

Clean, As- and P-terminated Si(1 0 0) surfaces were prepared with H ₂ carrier gas and AsH₃ and PH₃ as precursors in an MOCVD chamber. Reflectance difference spectra (RDS) were taken in situ. Samples were then transferred under vacuum to an ultrahigh-vacuum (UHV) chamber for analysis with AES, LEED, and STM. Clean, As-terminated Si(1 0 0) surfaces were achieved by annealing the sample at T < 900 °C supplying either AsH₃ or hydrogen (plus background As_x). Various preparation procedures were applied and benchmarked in UHV. Extended annealing under AsH₃ led to strongly faceted surfaces whereas AsH₃ flow of moderate concentration, temperature, and time led to flat, two-domain, (2 × 1)/(1 × 2) reconstructed surfaces. RD spectra almost identical to RD spectra of As/Si(1 0 0) surfaces prepared in UHV with MBE were obtained by annealing the samples under AsH₃. Annealing under PH₃ supply bore a new, two-domain (6 × 3)/(3 × 6) surface reconstruction at low flows, and a SiP compound at high flows.