Germanium-Silicon Quantum Dots Produced by Pulsed Laser Deposition for Photovoltaic Applications

Abstract

Quantum dots applied in solar cells will be of great importance to enhance the quantum tunneling efficiency and improve the photogenerated current transport. In this study, a new easy-to-operate technology was developed to fabricate germanium-silicon quantum dots in a SiOx matrix. The quantum dots were formed by first deposited germanium-rich SiO on quartz substrate using pulsed laser deposition technique and then annealed under a comparatively high temperature. We have demonstrated a stable and low-cost fabrication process which is much cheaper than the epitaxy method to provide for the fabrication of high density germanium-silicon quantum dots. Quantum dots with diameters of 3~4 nm embedded in the amorphous SiOx layer were clearly observed. The morphological features of the thin film were characterized. The optical properties were performed by Raman spectroscopy, photoluminescence spectrum and XRD test respectively to verify the crystallization of quantum dots in the SiOx matrix. Reflectance spectrum displayed a high light absorption rate in a spectra region from 300 nm to 1200 nm, evidencing that germanium-silicon quantum dots have promising features to be used as absorber for photovoltaic application.

Germanium Nanoparticles Prepared by Laser Ablation in Low Pressure Helium and Nitrogen Atmosphere for Biophotonic Applications

“…The advantage of this approach consists of ultraclean conditions of synthesis [ 25 ], which enables one to avoid all undesirable toxic impurities, typical for chemical routes. Several studies demonstrated the synthesis of Ge-based (Ge, GeO 2 , GeSi) nanocrystalline films [ 35 , 36 , 37 , 38 , 39 , 40 , 41 ] on the substrate or colloidal solutions of NPs [ 42 , 43 , 44 ] by using methods of pulsed laser ablation in gaseous or organic liquid media, respectively. Although such Ge crystallites may be of interest for optoelectronic, photovoltaic and other applications, their PL properties do not look promising for bioimaging use.…”

Raman study of laser-induced heating effects in free-standing silicon nanocrystals

“…Nanocrystals (NCs), also known as quantum dots (QDs), exhibit unique physical, mechanical and electrical properties since their excitons are confined in all three spatial dimensions. 1,2 NCs made of a variety of direct and indirect semiconductor materials have promising applications in the novel design of light emitting diodes (LEDs), 3 batteries, 4 solar cells 5,6 and water splitting devices. 7 For example, NCs might open routes to new photovoltaic (PV) concepts conquering the Shockley-Queisser limit 8 of single-junction solar cell devices, using mechanisms like multiple exciton generation (MEG) 9 and down conversion by space-separated quantum cutting (SSQC).…”

“…However, the extent of magnification is limited to the clear observation of a single NC with a diameter of a few nanometers (nm). High resolution transmission electron microscopy (HR-TEM) has a higher resolution and can even be utilized to investigate the lattice within the grains, 5,6 but it's more expensive in maintenance and more complex in preparing the samples for characterization. Especially when the Si NCs are embedded in a solid matrix, the quality of the final images is very sensitive to the ion-beam thinning technique during sample preparation.…”

Nanostructured germanium deposited on heated substrates with enhanced photoelectric properties

“…To produce high-quality Ge particles packed into different matrices, various approaches are reported in scientific papers such as pulsed laser deposition [20–21], sol–gel [22], evaporation under vacuum [23], chemical vapor deposition [24], microwave-assisted heating [25], implantation [26], RF magnetron sputtering [27]. However, for most of these approaches, thermal treatments were necessary after the deposition process in order to obtain high-quality nanostructures based on crystalline Ge [28].…”