Publication Date

1-24-2019

Department

Ames Laboratory; Physics and Astronomy; Electrical and Computer Engineering; Microelectronics Research Center (MRC)

Campus Units

Electrical and Computer Engineering, Physics and Astronomy, Ames Laboratory, Microelectronics Research Center (MRC)

OSTI ID+

1502872

Report Number

IS-J 9875

DOI

10.1007/s10854-019-00763-w

Journal Title

Journal of Materials Science: Materials in Electronics

Volume Number

30

Issue Number

5

First Page

4696

Last Page

4704

Abstract

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. Nanocrystalline-amorphous superlattices offer a unique pathway for synthesizing embedded nanocrystals with controlled sizes and photonic signatures.

DOE Contract Number(s)

DST/TM/SERI/2K11/78(G); ERIP/ER/0900376/M/01/1297; AC02-07CH11358

Language

en

Department of Energy Subject Categories

36 MATERIALS SCIENCE

Publisher

Iowa State University Digital Repository, Ames IA (United States)

Available for download on Friday, January 24, 2020

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