Photoluminescence studies of Si (100) doped with low-energy (≤1000 eV) As+ ions during molecular beam epitaxy

Abstract

Low-temperature (4.2K) photoluminescence (PL) has been used to characterize Si(100) films doped with EAs =200, 500, and 1000 eV 75 As+ ions during growth by molecular beam epitaxy on n+ Sb-doped substrates at temperatures Ts between 500 and 800 °C. Sharp no-phonon, transverse-optical, and transverse-acoustic phonon-assisted bound-exciton (BE) Peaks associated with As dopant species, together with broader, weaker, Sb-related BE peaks, were the dominant PL features obtained from 5-μm-thick layers. No peaks ascribable to residual ion-induced damage were observed in films grown at 650 °C with EAs =200 eV or Ts =800 °C with EAs =200, 500, and 1000 eV. However, reducing the film growth temperature to 500 °C with Eas =200 eV gave rise to a strong ion-damage PL peak at 1039.7 meV. Furthermore, both undoped and As ion-doped films grown at 500 °C exhibited a gradual increase in the PL background below 890 meV which we believe was due to quenched-in point defects. Complementary deep level transient spectroscopy measurements showed electron trap states (concentrations≂1014 cm−3) at energies of 0.06 an d-0.52 eV below the conduction-band edge for films grown at 500 °C with EAs =200 eV. No traps were observed in the ion-doped Ts=650 and 800 °C samples.