Lithography-Free Fabrication of Crystalline Silicon Nanowires Using Amorphous Silicon Substrate for Wide-Angle Energy Absorption Applications

We report a one-step fabrication technique of silicon nanowires using KrF excimer laser. Nanowires (NWs) are fabricated by redistributing the silicon mass within the sample without etching any of the deposited amorphous silicon (a-Si). Melting and resolidification of a-Si after multiple pulses laser irradiation induced the formation of NWs with lengths more than triple the thickness of the deposited film achieving a longer light path length. This resulted in a broadband absorption enhancement with reflection less than 5% for angle of incidences up to 60°. The effect of changing each laser parameter such as energy density, exposure time, and frequency on the morphology and optical properties of the NWs are systemically analyzed and compared.