Photoluminescent Properties of Hydrogenated Amorphous Silicon Oxide Powders

  • PDF / 97,745 Bytes
  • 4 Pages / 612 x 792 pts (letter) Page_size
  • 55 Downloads / 179 Views

DOWNLOAD

REPORT


The photoluminescence properties of hydrogenated amorphous silicon oxide powder SiO0.92H0.53 were investigated. The powder was prepared by reacting lithium with trichlorosilane in tetrahydrofuran. The luminescence peak energy was located between 1.0 and 1.61 eV. The samples were treated under different conditions such as annealing, hydrolysis, and hydrolysis plus HF etching. The changes of the photoluminescent intensity and location on the treated powders can be explained by the electronic density of state model of amorphous semiconductors. The temperature dependence of luminescence properties of the powders can be described by the relationship of thermal quenching effect: ln[Io/I(T ) − 1] ⳱ ED/Eo ⳱ T/To at temperatures between 100 and 300 K.

I. INTRODUCTION

II. EXPERIMENTAL

The formation of hydrogenated amorphous silicon nanopowder involved in the plasma-enhanced chemical vapor deposition (PECVD) process has been reported.1 This material is expected to be a good precursor in sintering ceramics and for catalytic surfaces. Similar to other silicon photoluminescent materials, such as amorphous silicon,2 porous silicon,3 and silicon nanocrystals,4 silicon nanopowders formed by PECVD showed an intense photoluminescence (PL) emission. However, their photoluminescences were qualitatively different. When hydrogenated amorphous silicon was alloyed with oxygen, the original network changed from a dense homogeneous phase to a less dense inhomogeneous and strained phase.5 Oxygen atom incorporation contributed to the changes of optical and electrical properties of those amorphous materials.6 We synthesized a disordered, nonregular structure of silicon-based photoluminescent materials using a simple wet chemical method by reacting lithium with trichlorosilane in tetrahydrofuran. These materials have a composition of SiO0.92H0.53 and exhibit a heterogenous structure with a-Si dispersed in SiO2 matrix.7 The changes of their photoluminescence properties under annealing, hydrolysis, and hydrolysis plus HF treatments were investigated to determine the luminescence mechanisms of the material.

Hydrogenated amorphous silicon oxide powders were synthesized by reacting lithium (99.9%, Aldrich Chemical Co., Milwaukee, WI) with trichlorosilane in tetrahydrofuran (THF; 99.9%, Fischer Chemical Co., Pittsburgh, PA) at room temperature under argon for 24 h with stirring. The annealed samples were prepared by heating the samples in a tube furnace under Ar at 5 °C/min from room temperature to the desired temperature, then held at temperature for 60 min. The hydrolyzed samples were prepared by stirring the synthesized powder in distilled water for 24 h. The HF etching was performed on hydrolyzed samples by dipping the samples in a 10% HF solution (diluted from 49.5% HF solution, Aldrich Chemical Co.) for 10 s. Photoluminescence measurements were performed in a vacuum chamber with the 488-nm line of an Ar ion laser as the excitation source.

a)

e-mail: [email protected] J. Mater. Res., Vol. 17, No. 5, May 2002

http://journals.cambridge.or