UV laser annealing of Diamond-Like Carbon layers obtained by Pulsed Laser Deposition for optical and photovoltaic applications

Abstract

One of the biggest challenge in optoelectronic devices is the necessity to provide a viable and reliable alternative to Transparent Conducting Oxide (TCO) and especially to Indium Tin Oxide (ITO). Graphene is a widely studied material and one of the best alternative to be used as conductive and transparent electrodes. It is well known that the difficulty to transfer graphene on another substrate is a serious limitation for its use on large scale devices. In this work, we explore Diamond-like Carbon (DLC) thin films prepared by Pulsed Laser Deposition (PLD) to be used as substrate for graphene-like layers. DLC thin films are excellent candidates due to their visible-range transparency being also a very good electrical insulator. Transmission measurements show the UV opaque character of the DLC layers, independently to the experimental parameters used to produce them. Thus, top-hat UV laser surface annealing can strongly modify the DLC thin film structure in order to bring conductivity to the first atomic layers. Raman spectroscopy and X-ray photoemission spectroscopy permit to confirm the graphitic character of the DLC surface. Optimizing PLD as well as laser annealing parameters is explored in detail in order to obtain comparable performances (conductivity and transparency) to ITO typical properties. Moreover, using a full-based laser process offers a complete compatibility with all technical steps of the microelectronic domain.