Improving photonic-electronic characteristics in quantum-dot solar cells via lattice strain mechanisms

Epitaxially formed indium arsenide quantum dot (QD) structures formed by the Stranski-Krastanov growth mode have been investigated with respect to how quantum confinement and lattice strain behavior affects the optoelectronic performance in p-i-n type InGaAs devices. The introduction of a correction layer and the proper selection of the QD capping layer’s alloy and thickness parameters allowed the control and management of the lattice misfit in two QD structures, which led to reduced defects and improved dark current behavior under forward bias conditions when compared to an InGaAs p-n homojunction (HOM) device without quantum-dots. Although the dark-current of the HOM devices behaved as expected under forward and reverse biases, the QD device structures displayed an apparent anomalous behavior in their dark-current densities under forward and reverse biases. Closer analysis reveals that this behavior is not anomalous; instead the information gained can be used to extract greater understanding about how to optimize the optoelectronic performance in quantum confined structures. In addition, the analysis suggests that lattice strain behavior continues to be a critical benchmark for defining and optimizing the performance of epitaxially formed= QD devices.