Date of Graduation

12-2014

Document Type

Thesis

Degree Name

Master of Science in Microelectronics-Photonics (MS)

Degree Level

Graduate

Department

Graduate School

Advisor

Hameed Naseem

Committee Member

Surendra Singh

Second Committee Member

Rick Wise

Third Committee Member

Ken Vickers

Keywords

Polysilicon, Silicon Nanowires, Solar cells

Abstract

Solar cells are photovoltaic devices that convert the energy of light to electricity by the photovoltaic effect. Crystalline silicon-based solar cells are the most dominant solar cells in the market today due to the high efficiency and relatively low cost. However, the cost of such solar cell is still high due to the large amount of material that is consumed in fabricating such a device. Polycrystalline/amorphous thin films and nanomaterial technologies have emerged to reduce the high cost of c-Si based solar cells and increase the efficiency. In this research, we combined these two technologies to propose and fabricate silicon nanowires (SiNWs)/amorphous Silicon (a-Si) composite solar cell structure at low temperatures using heavily doped polycrystalline silicon/glass as a substrate.

Silicon Nanowire (SiNW) is one of the promising 1D semiconductor nanomaterial which has recently attracted significant attention due to its potential applications in many fields, including photovoltaic (PV) solar cells. SiNW is a term that is used widely to describe a rod with a diameter of between 1 to 100 nm and length of several microns. The vertical array geometry of such a device has great advantages in increasing the efficiency of solar cells due to its high light absorption and efficient light scattering. Replacing the silicon with polycrystalline silicon that was fabricated on glass substrate by means of aluminum induced crystallization method of amorphous silicon is considered a significant step in reducing the cost since glass is a cheaper material. In this research, heavily doped polycrystalline (p+ polySi/ITO/glass) silicon film was fabricated successfully by the means of aluminum induced crystallization of a-Si on ITO/glass substrate. Raman spectroscope, optical microscope, Hall Effect measurement, and SEM were used for the characterizing the (p+ polySi/ITO/glass). P-type SiNW were grown successfully in the PECVD system on silicon, a-Si/ITO/glass, and p+ polySi/ITO/glass substrates using Au nanoparticles as a catalyst at temperatures between (310 ˚C and 346 ˚C). It is to be noted that this temperature range is still lower than the eutectic temperature of Au-Si (363 ˚C). SEM and TEM systems were used to characterize the SiNW on c-Si and p+ polySi/ITO/glass substrates.