Research Projects

The main motivation of this project is to make a simple photodetector based on semiconductor heterostructure (SHs) with advanced functionalities to be tested in a broad spectral range (Visible-Infrared (IR)). Aiming at IR photodetectors for its potential applications in optical communication, biomedical diagnostics, thermal imaging, and so on; we propose a collaborative fabrication technique (femtosecond laser writing and thin film deposition) to make SHs for device applications. Unlike conventional fabrication methods; which often comprise high-cost lithography, vacuum deposition, and complex post-processing; this technique offers a simple alternative for nanofabrication and device manufacturing by limiting the scalability and material flexibility. Here, a femtosecond laser beam is preferred for nanofabrication as it can enable highly localized, non-thermal, and ultrafast interactions with matter and produce laser-induced periodic surface structures (LIPSS). These structures (LIPSS) on Si and GaAs are essential for enhanced optical absorption and tunable broadband spectral response. In addition, the semiconductor LIPSS can offer several advantages over other existing surface structures that are mostly cleanroom-based, especially in terms of customizability of surface structures, single-step maskless patterning, greater light-trapping, and so on. Therefore, the laser-assisted semiconductors are facilitated to act as perfect templates for accommodating MoS₂ and/or WS₂ thin films (2D materials), leading to complete SHs. Here, we have chosen Si and GaAs as laser-processing substrates as they exhibit distinct complementary properties (electronic and optical), and MoS₂/ WS₂ as novel 2D materials, especially for IR photodetection. A similar methodology will be further explored for other photonic and optoelectronic device applications. There is a significant interest in this area in terms of fundamental understanding of nanostructured semiconductors and 2D materials for light-driven applications. Based on the literature survey conducted, we have developed this proposal considering the importance of laser-assisted SHs for photonic and optoelectronic applications.