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Journal of Undergraduate Research

Keywords

Plasma-Enhanced Chemical Vapor Deposition, PECVD, growth of nanocrystals, amorphous silicon film

College

Ira A. Fulton College of Engineering and Technology

Department

Electrical and Computer Engineering

Abstract

During Plasma-Enhanced Chemical Vapor Deposition (PECVD) crystal growth, an electric field between two charged plates dissociates a gas into a cloud of positive and negative ions called a plasma. The silicon ions descend to the silicon wafer and bond to the surface. Temperature is controlled and usually in the range of several hundred degrees celsius. Dispersed throughout the amorphous thin film are patches of crystalline structure that are nanometers in diameter. The goal of this project was to vary temperature, gas flow, gas mixture, gas pressure, and power settings on the PECVD system at BYU so as to consistently produce silicon nanocrystals of 2-3 nanometers in diameter with a density of 1012/cm2. It was expected that a temperature of 250 ºC, 3 sccm silane flow, 140 sccm hydrogen flow, 1500 mTorr of pressure, and 20 Watts of power would produce the desired crystal formations. Temperature increase, silane flow decrease, hydrogen flow increase, pressure increase, and an increase in power on the electrode plates were expected to decrease crystal size and increase density.

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