Amorphization of Indirect Band Gap Semiconductors To Tune Their Optoelectronic Properties
Oleksandr I. Malyi, Carlos Mera Acosta
Abstract
Historically, the search for prospective photovoltaic absorbers has been mainly focused on exploring different crystalline compounds having desired optoelectronic properties (e.g., a band gap energy of about 1.3 eV and high absorption coefficient) and composed primarily of inexpensive as well as environmentally friendly elements. In such explorations, special attention has been paid to the study of direct band gap materials or finding a way to make indirect band gap materials direct via doping or nanosizing. Herein, we propose amorphization as an effective way to tune the properties of indirect band gap materials. Specifically, we exemplify the effects for three representative compounds, namely, Si, SnS, and CuBiS2, demonstrating that their electronic structures can be adjusted to the extent of indirect–direct/near-direct band gap transition. More importantly, we reveal that this strategy can cause significant modification of interband transitions at the band edges, which can ultimately help to design a new generation of photovoltaic absorbers.