Date of Graduation

5-2015

Document Type

Thesis

Degree Name

Master of Science in Microelectronics-Photonics (MS)

Degree Level

Graduate

Department

Microelectronics-Photonics

Advisor/Mentor

Hameed Naseem

Committee Member

Shui-Qing (Fisher) Yu

Second Committee Member

Douglas Hutchings

Third Committee Member

Rick Wise

Keywords

Pure sciences, Applied sciences, Chemical vapor deposition, Epitaxial growth, Photovoltaics, Polycrystalline silicon

Abstract

There has been a growing interest in using low cost material as a substrate for the large grained polycrystalline silicon photovoltaic devices. The main property of those devices is the potential of obtaining high efficiency similar to crystalline Si devices efficiency yet at much lower cost because of the thin film techniques. Epitaxial growth of Si at low temperatures on low cost large grained seed layers, prepared by aluminum induced crystallization method (AIC), using hot wire chemical vapor deposition (HWCVD) system is investigated in this thesis. In this work, different parameters have been studied in order to optimize the growth to reach the goal of epitaxial growth. The growth of epitaxial silicon using HWCVD system is controlled by four parameters: flow rate of gases, pressure, substrate temperature and filament temperature. As a result, in this work, those four factors were varied to optimize the growth process.

Crystallinity quality is a significant factor toward confirming the epitaxial layer. Raman scattering, X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Transmission Electron Microscope (TEM) were used to determine the crystallinity. Epitaxial growth of Si at 500 °C was obtained even with a low vacuum of 1×10-3 torr.

Furthermore, heavily doped large grained polycrystalline silicon seed layers were formed at first using AIC on Indium Tin Oxide (ITO) coated glass substrates to be ready for the following step which was epitaxial growth of Si. The grains were continues in the center of the film which was a single crystal that no one has reported it before. Epitaxial growth of Si was successfully achieved as the SEM results showed similar grain sizes before the epitaxial growth and after the epitaxial growth. The TEM results confirmed the epitaxial growth but stacking faults were observed. Also, different orientations were present as Moiré Fringes was seen in the TEM images.

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