Light harvesting with Ge quantum dots embedded in SiO2 or Si3N4

Cosentino, Salvatore
Ozen, Emel Sungur
Raciti, Rosario
Mio, Antonio M.
Nicotra, Giuseppe
Simone, Francesca
Crupi, Isodiana
Turan, Raşit
Terrasi, Antonio
Mirabella, Salvo
Germanium quantum dots (QDs) embedded in SiO2 or in Si3N4 have been studied for light harvesting purposes. SiGeO or SiGeN thin films, produced by plasma enhanced chemical vapor deposition, have been annealed up to 850 degrees C to induce Ge QD precipitation in Si based matrices. By varying the Ge content, the QD diameter can be tuned in the 3-9 nm range in the SiO2 matrix, or in the 1-2 nm range in the Si3N4 matrix, as measured by transmission electron microscopy. Thus, Si3N4 matrix hosts Ge QDs at higher density and more closely spaced than SiO2 matrix. Raman spectroscopy revealed a higher threshold for amorphous-to-crystalline transition for Ge QDs embedded in Si3N4 matrix in comparison with those in the SiO2 host. Light absorption by Ge QDs is shown to be more effective in Si3N4 matrix, due to the optical bandgap (0.9-1.6 eV) being lower than in SiO2 matrix (1.2-2.2 eV). Significant photoresponse with a large measured internal quantum efficiency has been observed for Ge QDs in Si3N4 matrix when they are used as a sensitive layer in a photodetector device. These data will be presented and discussed, opening new routes for application of Ge QDs in light harvesting devices. (C) 2014 AIP Publishing LLC.


Photoluminescence properties of Si nanocrystals embedded in SiO2 matrix
Seyhan, Ayşe; Turan, Raşit; Department of Physics (2010)
This thesis examines the luminescence properties of nanoscale silicon (Si) by using spectroscopic techniques. Since the development of new optical devices requires understanding light emission mechanism optical spectroscopy has become more important tool in the analysis of these structures. In this thesis, Si nanocrystals embedded in SiO2 matrix will be studied. Photoluminescence (PL) and Time-resolved photoluminescence spectroscopy (TRPL) have been used to detect the light emission in UV-Vis-NIR range. Exp...
Optical properties of GaS crystals: Combined study of temperature-dependent band gap energy and oscillator parameters
IŞIK, MEHMET; TUĞAY, EVRİN; Hasanlı, Nızamı (2017-08-01)
Optical parameters of gallium sulfide (GaS) layered single crystals have been found through temperature-dependent transmission and room temperature reflection experiments in the wavelength range of 400-1100 nm. Experimental data demonstrates the coexistence of both optical indirect and direct transitions and the shift of the absorption edges toward lower energies by increasing temperature in the range of 10-300 K. Band gap at zero temperature, average phonon energy and electron phonon coupling parameter for...
Electroforming of Amorphous Silicon Nitride Heterojunction pin Visible Light Emitter
ANUTGAN, MUSTAFA; ANUTGAN, TAMİLA; ATILGAN, İSMAİL; Katircioglu, Bayram (2011-08-01)
The deposition parameters of doped hydrogenated nanocrystalline silicon grown by plasma-enhanced chemical vapor deposition were scanned to obtain highly conductive films. The optimized p(+) and n(+) nc-Si: H films were used as injecting layers in the fabrication of Si-rich hydrogenated amorphous silicon nitride (a-SiN(x) : H)-based heterojunction p(+) in(+) diode. The as-grown diode was subjected to a Joule-heating-assisted forming process (FP) via the application of a high electric field. The modifications...
Refractive index, static dielectric constant, energy band gap and oscillator parameters of Ga2SeS single crystals
Qasrawi, A. F.; Hasanlı, Nızamı (Wiley, 2007-09-01)
The optical properties of Bridgman method grown Ga2SeS crystals have been investigated by means of room-temperature transmittance and reflectance spectral analysis. The optical data have revealed direct and indirect allowed transition band gaps of 2.49 and 2.10 eV, respectively. The room-temperature refractive index, which was calculated from the reflectance and transmittance data, allowed the identification of the dispersion and oscillator energies, static dielectric constant and static refractive index as...
Emergence of 2MPA as an Effective Coating for Highly Stable and Luminescent Quantum Dots
Acar, Havva Yagci; Kas, Recep; Yurtsever, Ersin; Özen, Can; Lieberwirth, Ingo (2009-06-11)
3-Mercaptopropionic acid (3MPA) is a popular coating material for the preparation of aqueous quantum dots, yet its isomer 2-mercaptopropionic acid (2MPA) has not been much studied. Here, we present a detailed study on the aqueous synthesis of CdS quantum dots with a 2MPA coating. Reaction variables Such as the Cd/S ratio, 2MPA/Cd ratio, pH, and temperature were individually studied to evaluate the influence of these variables on particle size and luminescence. At the optimum ratios and reaction conditions, ...
Citation Formats
S. Cosentino et al., “Light harvesting with Ge quantum dots embedded in SiO2 or Si3N4,” JOURNAL OF APPLIED PHYSICS, pp. 0–0, 2014, Accessed: 00, 2020. [Online]. Available: