Naveen Narasimhachar Joshi1,Ben Sekely1,Pranay Kalakonda1,Sachin Kadian1,John Muth1,Roger Narayan1,Jagdish Narayan1
North Carolina State University1
Naveen Narasimhachar Joshi1,Ben Sekely1,Pranay Kalakonda1,Sachin Kadian1,John Muth1,Roger Narayan1,Jagdish Narayan1
North Carolina State University1
We report the formation of Si-DLC thin films on Si (100) and sapphire (0001) substrates via plasma-enhanced chemical vapor deposition (PECVD) technique. Subsequently, these thin films were irradiated with nanosecond ArF excimer laser pulses (λ = 193 nm; pulse duration = 20 ns) of varied energy density (0.6 Jcm<sup>-2</sup>. 0.7 Jcm<sup>-2</sup>, and 0.8 Jcm<sup>-2</sup>). The pulsed laser annealing (PLA) technique melts the Si-DLC films in a super-undercooled state that can be quenched rapidly. As such, the sp<sup>2</sup> content in the films can be modified by controlling the energy density of the laser pulse. We show that the optical bandgap of Si-DLC structures can be controlled by suitably tuning the sp<sup>2</sup> content in Si-DLC thin films through the PLA technique. Raman spectroscopy and XPS studies were employed to determine the sp<sup>2</sup>/sp<sup>3</sup> ratio in the as-deposited and PLA-treated Si-DLC thin films. Absorption spectra were obtained by UV-Vis spectroscopy and used to determine the optical bandgap (Tauc’s method) and Urbach energy and correlated with the sp<sup>2</sup> content in the films. This study shows that PLA is a powerful technique for controlling the functional properties of DLC thin films for state-of-the-art optoelectronic applications.