Luminescence from porous layers produced by Ag‐assisted electroless etching

Abstract

Porous layers were formed on highly resistive p-type silicon by an Ag-assisted electroless etching method using a chemical solution of HF and K 2 Cr 2 O 7 . The porous silicon (PS) layer formed by this method as a function of etching time was investigated by scanning electron microscopy (SEM) and backscattering spectrometry (BS) in random and channelling mode. Channelling spectra show that the porous layer remains crystalline after etching. On the other hand, random and channelling spectra show that the deposited silver diffuses into the pore. Luminescence from Ag-assisted chemically etched layers was measured. It was found that the photoluminescence spectra strongly depend on etching time. Indeed, for etching time lower than 60 min, the PL emission is in the blue region with a peak located at 450 nm. In addition, for an etching time of 60 min or higher, the PL peak is centred at about 630 nm.

Silicon Porosification: State of the Art

“…261,270,278 It is interesting that PL of PSi prepared using metal assisted etching has specific features in comparison with PSi prepared using anodic etching. Hadjersi and Gabouze 277 have shown that the evolution of PL intensity with etching time can be divided into two phases. In the first phase the emission is in the blue region.…”

“…Moreover, using metal-assisted stain etching porous silicon layers have been formed on highly resistive silicon, which are difficult to produce by the electrochemical etching. 277 Furthermore, compared to stain etched layers, galvanically formed porous layers have better uniformity and much bigger thickness. 261 Last years this method was successfully used in photonic, photovoltaic, or diffusion membrane applications.…”

“…277 Depending on the type of metal deposited and Si doping type and doping level, PSi films with different morphologies and light-emitting properties were produced on both p-and n-type Si. 218 For example, Au is found to form a more columnar structure as opposed to a spongy structure for Pt during etching in HF/H 2 O 2 solution.…”

Porous Silicon Formation by Metal Nanoparticle-Assisted Etching

“…Metal-assisted etching is frequently used to prepare photoluminescent porous Si (Dimova-Malinovska et al 1997;Li and Bohn 2000;Harada et al 2001;Chattopadhyay et al 2002;Hadjersi et al 2004, Hadjersi et al 2005bHadjersi 2007;Megouda et al 2009b;Zhao et al 2007;Gorostiza et al 1999;Chattopadhyay and Bohn 2006;Hadjersi and Gabouze 2007;Lipinski et al 2009). MAE displays little crystallographic dependence and can be performed on crystalline or multicrystalline Si substrates, and the various Si morphologies and nanomicrostructures obtained are promising for photovoltaic applications in several areas: antireflective coating (Yae et al 2003(Yae et al , 2005(Yae et al , 2006Peng et al 2005a, b;Benoit et al 2008;Lu and Barron 2013;Tsujino and Matsumura 2006b;Chaoui et al 2008;Nishioka et al 2008Nishioka et al , 2009Srivastava et al 2010;Cao et al 2011;Kim et al 2011Kim et al , 2012Geng et al 2012;Wang et al 2013b;Li et al 2013a), texturization for multicrystalline wafers (Tsujino and Matsumura 2006a;Waheed et al 2010;Branz et al 2009;Li et al 2012;Wan et al 2008;Koynov et al 2006Koynov et al , 2007Lipiński 2008;…”

Formation of aligned silicon nanowire on silicon by electroless etching in HF solution

“…However, it provides PL intensities in an order of magnitude smaller than conventional electrochemically etched PS [5]. Recently, we have used a new metal-assisted electroless etching method [6], developed previously by Li and Bohn [7] to produce visible-light-emitting layers. It needs no electrodes on the back surface of silicon wafers and enables formation of uniform porous silicon layers.…”