Defects porous silicon

Ongoing investigations into the chemistry of porous silicon surfaces seek to develop methods for the preparation of chemically functional interfaces that protect the underlying silicon nanocrystallites from degradation without changing or annihilating their intrinsic behavior. The native, hydride-terminated surface is only metastable under ambient conditions and oxidation of freshly prepared porous silicon commences within minutes when exposed to air. While surface oxide can suitably passivate the nanocrystalline silicon and stabilize its photoluminescence, the electrically insulating and structurally defective character of this oxide layer... 

Stievenard, D. and Deresmes, D. Identification of a defect in porous silicon , (1995) Appl. Phys. Lett. 67,1570-2. 

Since the discovery of the intense red photoluminescence of porous silicon [1,2], much work has been devoted to this particular nanostructured material [4, 5] and, in the meantime, also to silicon nanoparticles [6, 7]. An important issue of current studies is the influence of the surface passivation on the photoluminescence properties. It has already been said that, in the quantum confinement model, it is essential that the surface is well passivated to avoid any dangling bonds [8]. Being middle-gap defects, these dangling bonds will quench the PL. On the other hand, the surface itself may lead to surface states that can be the origin of another kind of photoluminescence [9,10]. 

Summarizing, photoinduced and ion or electron beam effects include oxidation, hydrogen release, dangling bond creation, and creation of reactive molecular species. Ion bombardment can in addition introduce a variety of point defects in the silicon skeleton. Highly focused beams, such as used in micro-Raman, can cause thermally induced hydrogen exodiffusion, sintering, defect creation, etc. An awareness of potential irradiation effects is important in both the characterization and processing of porous silicon. 

Du XW, Jin Y, Zhao NQ, Fu YS, Kulinich SA (2008) Controlling surface states and photoluminescence of porous silicon by low-energy-ion irradiation. Appl Surf Sci 254(8) 2479-2482 El Houichet H, Oueslati M, Bessais B, Ezzaouia H (1997) Photoluminescence enhancement and degradation in porous silicon evidence for nonconventional photoinduced defects. J Lumin... 

The literature on epitaxial growth of different materials on porous silicon substrate has been surveyed. This field was stimulated by the theoretical prediction in 1986 of stress field and hence defect reduction in lattice-mismatched film grown on a mesoporous substrate. Data now exists not only on Ge, SiC, and diamond films but also on a range of both III-V and II-VI semiconductors, as well as other crystalline materials. Recently there has been most interest in GaN growth on porous silicon for optoelectronic applications. 

In the following, the quahty of epitaxial Si layers deposited either on an annealed porous Si layer or on a non-annealed porous Si layer is discussed. The epitaxial layer quality is evaluated by etch pit densities, defect densities, minority carrier lifetimes, or solar cell efficiencies. Table 1 gives an overview on the main characteristics of the epitaxial Si layers on the different types of porous silicon layers, i.e., single or double layers. 

Bardeleben HJ, Cantin JL (1997) Paramagnetic defects in porous silicon. In Canham LT (ed) Properties of porous silicon. INSPEC, London... 

Woo TK, Kim SE, Ahn HS (2012b) Experimentally derived catalytic etching kinetics for defect-utilized dual-porous silicon formation. J Phys Chem C 116 7040-7049... 

Radhakrishnan HS, Ahn C, Van Hoeymissen J, Dross F, Cowem N, Van Nieuwenhuysen K, Gordon I, Mertens R, Poortmans J (2012) Gettering of transition metals by porous silicon in epitaxial silicon solar cells. Phys Status Solid (a). doi 10.1002/pssa.201200232,209 1866-1871 Rohatgi A, Davis JR, Hopkins RH, McMullin PG (1983) A study of grown-in impurities in silicon by deep-level transient spectroscopy. Solid State Electron 26 1039 Schindler R (1994) The art of living with defects in silicon gettering and passivation. Solid State Phenom 37 343... 

In Silicon nanocrystals (2010). WILEY-VCH Verlag GmbH Co. KGaA, Weinheim Perez K, Estevez JO, Mendez-Blas A, Arriaga J (2012) Localized defect modes in dual-periodical multilayer structures based on porous silicon. J Opt Soc Am B 29(4) 538-542 Prasad PN (ed) (2004) Chapter 9. Photonic crystals. In Nanophotonic. John Wiley Sons, Inc., Hoboken, New Jersey, Canada... 

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