Can chemically etched germanium or germanium nanocrystals emit visible photoluminescence?

Abstract

Photoluminescence (PL) properties of various Ge‐based nanostructured materials, prepared using methods such as chemical etching, ion implantation and spark processing, have been studied. The PL was much stronger from the samples containing Ge nanocrystals, in comparison with their counterparts with no or less Ge nanoparticles, hinting at the likely role of the quantum confinement in Ge nanocrystals (NCs) in the light emission process. On the other hand, defects in the oxides or Ge–O bonded material alone are also shown to emit light in the same energy zone as with the Ge NCs. Discussion on these results is presented. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Ge Nanoislands Grown by Radio Frequency Magnetron Sputtering: Comprehensive Investigation of Surface Morphology and Optical Properties

“…The first order transverse optical (TO) phonon mode of Ge nanoisland occurred at ∼302 cm −1 which is in conformity with the results of Kartopu et al [39]. A shift for strongest Raman peak at ∼302 cm −1 corresponding to the Ge-Ge phonon mode towards higher frequency with respect to the bulk crystalline Ge which is expected to occur at ∼300 cm −1 is ascribed to the competitive effect of strain and phonon confinement.…”

Fabrication and characteristics of porous germanium films

“…The use of short-wavelength excitation (325 nm) and 12-µm-thick film enabled measurement of the Raman signal from the top layer without significant contribution from the underlying substrate [28] (spectra a and b). Ge-O and Ge-O-Ge bonds cause Raman scattering peaks at 211, 246, 262, 327 and 442 cm −1 [16,20]. Such peaks are not observed in spectra a and b, confirming that the film unlikely contains oxygen.…”

“…It has been particularly challenging to synthesize group IV materials, such as Si and Ge, primarily owing to their strong covalent bonding and the need for high temperatures to promote crystallization [11][12][13]. Anodization and electrochemical etching [3,[14][15][16][17][18], spark processing [19,20] and inductively coupled plasma chemical vapor deposition (ICPCVD) [2,21] have been used to prepare porous Ge films. It is still a challenge to produce porous, semiconducting and luminescent Ge films in a simple and robust way, allowing their subsequent processing and integration into working devices [1][2][3][14][15][16][17][18][19][20].…”

“…Anodization and electrochemical etching [3,[14][15][16][17][18], spark processing [19,20] and inductively coupled plasma chemical vapor deposition (ICPCVD) [2,21] have been used to prepare porous Ge films. It is still a challenge to produce porous, semiconducting and luminescent Ge films in a simple and robust way, allowing their subsequent processing and integration into working devices [1][2][3][14][15][16][17][18][19][20]. The porous structure plays an important role in the visible PL emission of the indirect bandgap semiconductors, such as Si and Ge [4][5][6][14][15][16][17][18][19][20].…”

“…It is still a challenge to produce porous, semiconducting and luminescent Ge films in a simple and robust way, allowing their subsequent processing and integration into working devices [1][2][3][14][15][16][17][18][19][20]. The porous structure plays an important role in the visible PL emission of the indirect bandgap semiconductors, such as Si and Ge [4][5][6][14][15][16][17][18][19][20]. Formation of porous structures likely enhances electrical resistivity and carrier scattering rate, hindering measurements of the transport properties; it also may decrease the adhesion between the film and substrate.…”