Photoluminescence from Si(001) films doped with 100–1000 eV B+ ions during deposition by molecular beam epitaxy

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Abstract
Temperature-dependent photoluminescence (PL) measurements have been used to characterize 5-μm-thick Si(001) layers doped with low-energy 11B+ ions (EB+=100, 500, and 1000 eV) during molecular beam epitaxy (MBE) at growth temperatures Ts=500, 650, and 800 °C. Films deposited at 800 °C with EB+=100 and 500 eV exhibited spectra comparable to bulk Si with narrow intense B1TO exciton recombination peaks together with multiple-exciton B2TO and B3TO peaks as well as free-exciton FETO, BTO+Or1, BTO(2h), B1TA, and B1LO peaks showing that the films are of very high quality. The overall luminescence intensity was found to decrease with decreasing Ts and increasing EB+. PL spectra from films grown at the lowest temperature, Ts=500 °C, were quite different in appearance with very weak bound-exciton peaks and additional features, I3 and I3TA, near 1040 meV due to residual ion-induced damage which increased in intensity with increasing EB+. Compared to As+ ion doping, lower ion energies and/or higher growth temperatures are required to avoid residual ion-induced damage in B+ ion-doped MBE Si(001). Post-annealing experiments showed no detectable residual ion-induced lattice damage in B+-doped, Ts=500 °C, films after 15 min at 800 °C.