الفهرس 
Chapter 1 IntroductionOnly 14 pages are availabe for public view
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Abstract
The objectives of this dissertation are designing, simulating, and characterizing recent, efficient and different approaches for energy harvesting. The PV devices based on Silicon nanowires (Si NWs) have attracted a great attention due to their outstanding optical and electrical properties. This is due to the physical geometry of the NWs which decreases the reflection and improves the effective absorption length in the longitudinal direction. In this thesis, the optical and electrical performances of Si NW solar cells have been studied through the diversity of both configuration and design. The new design is formed of Si NWs arranged in a funnel-shaped. The p-n radial and axial junctions are examined using finite element via Lumerical Device software package in an attempt to pave the road for ultra-high efficiency Si NWs devices for solar cell applications. In this regard, short circuit current density, open circuit voltage, fill factor and power conversion efficiency are simulated to quantify the optoelectronic performance of the reported design. Furthermore, the effects of the doping concentration and carrier lifetime on the performance of the funnel-shaped design are reported. On the other hand, the optical characteristics of star-shaped (Si NWs) solar cells using 3D finite difference time domain (FDTD) are also investigated. The Particle Swarm Optimization (PSO) technique is used to optimize the geometrical parameters of the suggested design. The optical study reveals that the optimized star-shaped Si NWs can offer an ultimate efficiency of 43.7% with short circuit current density of 35.76 mA/cm2 while its complementary design achieves an ultimate efficiency of 40.1% with short circuit current density of 32.8 mA/cm2. The electrical properties are calculated using finite element method via Lumerical Device software package. The short circuit current density, open circuit voltage, fill factor and power conversion efficiency are simulated to quantify the optoelectronic performance of the optimized design. Furthermore, the doping level of the optimized star-shaped design with p-i-n axial and radial configurations is reported.