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Type: 
Journal
Description: 
Germanium quantum dots (QDs) embedded in SiO {sub 2} or in Si {sub 3} N {sub 4} 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 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 SiO {sub 2} matrix, or in the 1–2 nm range in the Si {sub 3} N {sub 4} matrix, as measured by transmission electron microscopy. Thus, Si {sub 3} N {sub 4} matrix hosts Ge QDs at higher density and more closely spaced than SiO {sub 2} matrix. Raman spectroscopy revealed a higher threshold for amorphous-to-crystalline transition for Ge QDs embedded in Si {sub 3} N {sub 4} matrix in comparison with those in the SiO {sub 2} host. Light absorption by Ge QDs is shown to be more effective in Si {sub 3} N {sub 4} matrix, due to the optical bandgap (0.9–1.6 eV) being lower than in SiO {sub 2} matrix (1.2–2.2 eV). Significant photoresponse with a large measured internal quantum efficiency has been observed for Ge QDs in Si {sub 3} N {sub 4} matrix when they are used as a sensitive layer in a photodetector device. These data will be presented and discussed, opening more»
Publisher: 
Publication date: 
28 Jan 2014
Authors: 

Salvatore Cosentino, Rosario Raciti, Francesca Simone, Isodiana Crupi, Antonio Terrasi, Salvo Mirabella, Emel Sungur Ozen, Atilla Aydinli, Antonio M Mio, Giuseppe Nicotra, Rasit Turan

Biblio References: 
Volume: 115 Issue: 4
Origin: 
Journal of Applied Physics