Simulation and Fabrication of Defect Tolerant High Efficiency Epitaxial III-V Photovoltaics

The goal of this dissertation is to establish a pathway towards development of cost-effective high efficiency III-V photovoltaics. Combining the unsurpassed performance of GaAs based multi-junction technologies with a conventional cheap roll to roll processing standards of thin film industry could lead to paradigm-shifting reduction of the cost of solar electricity. Growth of III-V on polycrystalline flexible substrates provides a path towards this goal, but is limited by high dislocation densities, which leads to minimal efficiency using conventional device designs. In this work we will focus on strategies for development of thinner (reduced process time) and more defect tolerant devices, that could deliver higher efficiencies on flexible substrates. This work has shown single crystalline like GaAs epilayers on polycrystalline flexible templates, and within this framework has demonstrated theoretically and experimentally possibility of increasing efficiencies by more than two folds than their conventional thin film counterparts (in presence of dislocations in excess of 10^8cm-2). Using defect tolerant designs for ultra-thin tandem design, efficiencies in excess of 25% can be achieved on flexible templates.Electrical and Computer Engineering, Department o