Photoluminescence and Auger spectroscopy of porous Si: Solvent, reactive ion etching, annealing, and substrate boron level effects

The blueshift results from the higher H/Si ratio; the invariant yield is believed to be limited by the density of dangling bonds at the SiOxHy/Si interface which is apparently unaffected by the treatments. It is therefore believed that the PL is at least partially due to SiHx or SiOxHy complexes on the crystallite and column surfaces, which are similar to those found at the surface of some H-rich a-Si:H. Size effects, however, cannot be ruled out. In contrast to films etched from 7 to 20 Ω cm wafers, λmax of those prepared from 1 to 2 Ω cm substrates was consistently ∼7000 A after a brief exposure to air. While η exhibited a complex dependence on the O2 RIE power, λmax was unchanged by either O2 or H2 plasmas. The emission from heavily doped ∼0.02 Ω cm films was usually undetectable. However, H2 RIE resulted in observable PL