Quantum confinement effect of silicon nanocrystals in situ grown in silicon nitride films
- PDF / 178,319 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 28 Downloads / 178 Views
L4.3.1
Quantum confinement effect of silicon nanocrystals in situ grown in silicon nitride films Tae-Youb Kim, Nae-Man Park, Kyung-Hyun Kim, Young-Woo Ok1, Tae-Yeon Seong1, CheolJong Choi2 and Gun Yong Sung Future Technology Research Division, Electronics and Telecommunication Research Institute, Daejon, 305-350, Korea 1 Department of Materials Science and Engineering, Kwangju Institute of Science and Technology, Kwangju 500-712, Korea 2 Samsung Advanced Institute of Technology, Yongin Gyeonggi-do 449-712, Korea ABSTRACT Silicon nanocrystals were in situ grown in a silicon nitride film by plasma enhanced chemical vapor deposition. The size and structure of silicon nanocrystals were confirmed by highresolution transmission electron microscopy. Depending on the size, the photoluminescence of silicon nanocrystals can be tuned from the near infrared (1.38 eV) to the ultraviolet (3.02 eV). The fitted photoluminescence peak energy as E(eV) = 1.16 + 11.8/d2 is an evidence for the quantum confinement effect in silicon nanocrystals. The results demonstrate that the band gap of silicon nanocrystals embedded in silicon nitride matrix was more effectively controlled for a wide range of luminescent wavelengths.
INTRODUCTION Because of its indirect band gap of 1.1 eV, silicon is characterized as having a very poor optical radiative efficiency and only produces light outside the visible range. Silicon nanostructures, however, which show a quantum confinement effect have an enhanced rate of electron-hole radiative recombination [1]. In recent years, a great deal of research on silicon nanocrystals embedded in a silicon oxide matrix have been conducted because of their potential for applications in silicon-based optoelectronic devices [2-3]. However, a number of groups have reported that when the crystallite size of silicon nanostructures in a silicon oxide matrix is controlled, the experimental photoluminescence energies in air are not in good agreement with values that are theoretically calculated from quantum confinement effects [4-5]. Wolkin et al. proposed that oxygen is related to the trapping of an electron (or even an exciton) by silicon-
L4.3.2
oxygen double bonds and produces localized levels in the bandgap of nanocrystals [6]. Therefore, a quantum confinement effect is not good agreement with the theoretical calculation in silicon nanostructures, after exposure to air [7-8]. Even when a silicon oxide is used as a typical matrix material that hosts silicon nanostructures, a silicon oxide matrix may not provide an appropriate emission state for a quantum confinement effect in small silicon crystallites. Because of this, the focus of the present study was on an appropriate matrix material for silicon nanocrystals. There appear to be few localized states that correlate with the optical process of carriers at a nanocrystal surface in a silicon nitride matrix, as shown in a previous report related to amorphous silicon quantum dot structures [9-10]. In the present work, we report on silicon nanocrystals that were in situ gr
Data Loading...
