Formation of Si and Ge quantum structures by laser‐induced etching

Abstract

Quantum structures were fabricated by immersing a crystalline silicon (Si) or germanium (Ge) wafer in hydrofluoric acid followed by laser‐induced etching with a laser photon energy of 2.41 eV. Atomic force microscopy (AFM) investigations of Si(100) etched samples reveal a complex surface morphology with pits from the top view and pillar‐like structures from the three‐dimensional view of the pit wall. For Ge(111) laser‐etched samples, AFM shows parallel wall‐type structures and Ge quantum structures on the surface of the walls. Laser‐induced etching of Ge is reported for the first time. Observation of photoluminescence spectra from both samples confirms the presence of quantum confined structures. Line‐shape analysis of Raman spectra is used to estimate the size of the quantum structures. The sizes of nanoparticles can be controlled by the laser power density and irradiation time for etching. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Silicon Porosification: State of the Art

“…253,255,256 In particular, Kumar et al 251 have shown that, depending upon the laser power density, different etching stages can form cracks, pores, and pillar-like structures on the Si wafer. To get the porous structures, the laser power density should neither be very low nor very high.…”

“…Typical PL spectra of PSi prepared by laser induced etching by Shin et al 253 are shown in Figure 23.…”

Porous Silicon Formation by Photoetching

“…A summary of PS formation by photoetching is presented in Tables 1 and 2 (Xu and Adachi Adachi and Kubota 2007;Tomioka et al 2007;Andersen et al 1995;Noguchi and Suemune 1993;Zhang et al 1993;Cheah and Choy 1994;Jones et al 1996;Kolasinski et al 2000;Takai 2000, 2001;Mavi et al 2001Mavi et al , 2006Marotti et al 2003;Cho et al 2006;Xu and Adachi 2008;Matsui and Adachi 2012;Zheng et al 2005;Adachi and Tomioka 2005).…”

Luminescent Properties of Porous Silicon

“…Analysis of the PSi layer morphology has shown that the structure of the porous layer during laser-induced etching can be controlled by the excitation laser power density, etching time, concentration of etchant, and wavelength of laser source used (Wellner et al 2000;Rasheed et al 2001;Mavi et al 2006). In particular, Kumar et al (2008) have shown that depending on the laser power density, different etching stages naming cracks, pores, and pillar-like structures can be formed on the Si wafer.…”

“…We need to note that the feature mentioned above (of PSi layer formed by laserinduced etching) may be considered a disadvantage of the discussed method of Si porosification. Typical PL spectra of PSi prepared by laser-induced etching by Mavi et al (2006) are shown in Figure 10.16.…”