Pulsed Laser Deposition and Characterization of Diamond-like Carbon and Graphitic Thin Films and Graphene
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The present work aims towards the fabrication and characterization of diamond-like carbon (DLC) and graphitic thin films and few-/multi-layer graphene via pulsed laser deposition (PLD) technique. The structural characterization of all the films fabricated via PLD was performed by Raman spectrometer. The intensity of the excitation laser source while recording the Raman spectra of DLC films plays a crucial role in the correct measurement of film quality. It was observed that upto the laser intensity of 114 kW/cm2, there was not much significant changes in the Raman spectra while above this, the spectra was drastically modified indicating the effect of focal heating and these changes in the film are of permanent nature. Thus, the Raman spectra reported in the entire thesis were recorded at a laser intensity of 114 kW/cm2.The effect of deposition parameters; substrate temperature, laser fluence and the background helium gas pressure on the DLC film was undertaken in detail. It was observed that the low substrate temperature favoured the formation of carbon film dominated by sp3 bonding while the film deposited at higher temperature, 700 °C and above, exhibited the graphitic nature. The variation in sp3 fraction of the DLC thin film was more pronounced as a function of helium pressure as compared to that of laser fluence. The higher pressure of helium gas was observed to favour the structural ordering of graphitic thin films deposited at 750 °C.
Supervisor: Alika Khare