Nanotexturing of Diamond Surfaces via Ultra-Short Laser Pulses Inducing Enhanced Optical and Electronic Properties

One of the main advantages of using ultra-short laser pulses is the capability to minimize unwanted thermal effects during surface material processing, instead occurring when longer laser beam pulses are employed. Indeed, ultra-short laser pulses, delivering extremely high radiation powers, trigger non-linear effects like multiphotonic absorption which lead towards a strong laser-matter interaction, even for dielectrics and wide bandgap semiconductors, such as diamond.<br/>In the last decades, the use of ultra-short laser pulses paved the way for accurate diamond micro- and nano-structuring, thanks to the effective formation of Laser-Induced Periodic Surface Structures (LIPSS). The creation of subwavelength LIPSS through lasers allows a straightforward engineering of the diamond's electronic bandgap that is crucial for developing diamond-based optoelectronic devices.<br/>A specific case of surface texturing with a defined subwavelength periodicity of the diamond surface is represented by the development of “black diamond” films, i.e., diamond films with drastically enhanced optical and electronic properties, developed by the authors’ group.<br/>The texturing at the nanoscale and the significant improvement in the photoelectronic sensitivity for photons with sub-bandgap energy open the applicability for visible wavelength band optics, where the exceptional resilience of diamond is an added value. In this framework, the most direct application of surface-treated thin diamond film at the nanoscales is as antireflection coatings and selective absorbers for thermal solar applications.<br/>Regarding specific applications, our group has proposed LIPSS on diamond for the development of high-temperature solar cells, as well as advanced opto-electronic platforms and photo-electro-chemical devices. With this aim, a strategy of defect-engineering is pursued for the fabrication of black diamond-based devices, with the possibility of locally controlling the optical, electronic, and chemical properties of diamond opening new perspective to functional enhancements of wide band gap materials.