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Title: Quantum size effects and tunable visible photoluminescence in a-Si:H/nc-Si:H superlattices

Quantum size effects are commonly observed in semiconductor nanocrystals and quantum dots. Here, we demonstrate unexpected quantum size effects in an unusual bulk system with multiple interfaces, consisting of alternating layers of nanocrystalline silicon (nc-Si:H) and amorphous silicon (a-Si:H) material thin films. The nc-Si:H layers consist of silicon nanocrystals embedded in an amorphous matrix, with an amorphous-crystalline interface separating the two structures. Plasma-enhanced chemical vapor deposition was utilized to grow nanocrystalline-amorphous silicon superlattices with a varying thickness of the nanocrystalline layer. Strong visible photoluminescence at room temperature was deconvoluted into individual peaks. As the nanocrystalline silicon layer thickness was increased from 5 to 20 nm, the photoluminescence spectra red-shifted with the emission wavelength varying as d 2 (d is the size of the nanocrystallites), the characteristic signature underlying quantum size effects. The size d of the nanocrystals was estimated by the measured shift of the Raman peak, and could be tuned by varying the thickness of the nc-Si:H layers. High resolution transmission electron microscopy show nanocrystals with a narrow size distribution, in an amorphous matrix. We also observe long wavelength photoluminescence from interfacial states that leads to persistent photconductivity. In conclusion nanocrystalline-amorphous superlattices offer a unique pathway for synthesizing embeddedmore » nanocrystals with controlled sizes and photonic signatures.« less
Authors:
 [1] ;  [1] ;  [2]
  1. Indian Institute of Technology Guwahati, Guwahati (India)
  2. Ames Lab. and Iowa State Univ., Ames, IA (United States)
Publication Date:
Report Number(s):
IS-J-9875
Journal ID: ISSN 0957-4522
Grant/Contract Number:
DST/TM/SERI/2K11/78(G); ERIP/ER/0900376/M/01/1297; AC02-07CH11358
Type:
Accepted Manuscript
Journal Name:
Journal of Materials Science Materials in Electronics
Additional Journal Information:
Journal Volume: 30; Journal Issue: 5; Journal ID: ISSN 0957-4522
Publisher:
Springer
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1502872

Yadav, Asha, Agarwal, Pratima, and Biswas, Rana. Quantum size effects and tunable visible photoluminescence in a-Si:H/nc-Si:H superlattices. United States: N. p., Web. doi:10.1007/s10854-019-00763-w.
Yadav, Asha, Agarwal, Pratima, & Biswas, Rana. Quantum size effects and tunable visible photoluminescence in a-Si:H/nc-Si:H superlattices. United States. doi:10.1007/s10854-019-00763-w.
Yadav, Asha, Agarwal, Pratima, and Biswas, Rana. 2019. "Quantum size effects and tunable visible photoluminescence in a-Si:H/nc-Si:H superlattices". United States. doi:10.1007/s10854-019-00763-w.
@article{osti_1502872,
title = {Quantum size effects and tunable visible photoluminescence in a-Si:H/nc-Si:H superlattices},
author = {Yadav, Asha and Agarwal, Pratima and Biswas, Rana},
abstractNote = {Quantum size effects are commonly observed in semiconductor nanocrystals and quantum dots. Here, we demonstrate unexpected quantum size effects in an unusual bulk system with multiple interfaces, consisting of alternating layers of nanocrystalline silicon (nc-Si:H) and amorphous silicon (a-Si:H) material thin films. The nc-Si:H layers consist of silicon nanocrystals embedded in an amorphous matrix, with an amorphous-crystalline interface separating the two structures. Plasma-enhanced chemical vapor deposition was utilized to grow nanocrystalline-amorphous silicon superlattices with a varying thickness of the nanocrystalline layer. Strong visible photoluminescence at room temperature was deconvoluted into individual peaks. As the nanocrystalline silicon layer thickness was increased from 5 to 20 nm, the photoluminescence spectra red-shifted with the emission wavelength varying as d2 (d is the size of the nanocrystallites), the characteristic signature underlying quantum size effects. The size d of the nanocrystals was estimated by the measured shift of the Raman peak, and could be tuned by varying the thickness of the nc-Si:H layers. High resolution transmission electron microscopy show nanocrystals with a narrow size distribution, in an amorphous matrix. We also observe long wavelength photoluminescence from interfacial states that leads to persistent photconductivity. In conclusion nanocrystalline-amorphous superlattices offer a unique pathway for synthesizing embedded nanocrystals with controlled sizes and photonic signatures.},
doi = {10.1007/s10854-019-00763-w},
journal = {Journal of Materials Science Materials in Electronics},
number = 5,
volume = 30,
place = {United States},
year = {2019},
month = {1}
}

Works referenced in this record:

Silicon quantum wire array fabrication by electrochemical and chemical dissolution of wafers
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