Self-assembled Cu(In,Ga)Se ₂ nanocrystals formed by Ar ion beam irradiation

We developed a simple and effective method for the large scale formation of self-assembled Cu(In,Ga)Se ₂ (CIGS) nanocrystals by ion beam irradiation. The compositional changes and morphological evolution were observed as a function of the irradiation time. As the ion irradiation time increased, the nano-dots were transformed into a nano-ridge structure due to the competition between sputtering and diffusion processes during irradiation. In terms of the stoichiometry of the CIGS nano-dots, an increase in the Cu content was observed while the Se content decreased. The PL peak of the nano-dots formed CIGS thin film exhibited a blue-shift. Uniformly formed crystalline CIGS nano-dots can be adopted to increase the p-n junction area and the size confinement effect between the CdS and CIGS film in solar cell systems. This simple method can be exploited for band-gap engineering and enhancing photovoltaic properties.