Anti-reflection structures fabricated by direct laser interference technology under different ambiances

In this paper, we take the strategy of direct laser interference technology to modify the silicon surface under air and sulphur hexafluoride (SF₆) gas ambiance conditions. With the investigation of optical properties, the silicon spike structures (known as black silicon) which were fabricated in the SF₆ ambiance showed the excellent ability of reducing light reflection with a broadband spectrum. For comparison, well-defined microcone structures were fabricated in the air ambiance. After hydrofluoric (HF) acid wiping off the oxides on the surface, micro cone structures have shown the anti-reflection function as well and its reflective behaviour was dependent on the structural depth relatively. Due to a high impurities concentration of spike structures obtained in the SF₆ ambiance, applications of sulphur-doped black silicon would be limited. To obtain large-scale uniform structures, direct laser interference technology in the air ambiance could be an alternative.