Boron carbide thin films deposited by RF-PECVD and PLD technique: A comparative study based on structure, optical properties, and residual stress

Abstract

Radio-Frequency Plasma Enhanced Chemical Vapour Deposition (RF-PECVD), and Pulsed Laser Deposition (PLD) techniques were used to deposit boron carbide (BxC) thin films. Films were investigated to compare crystallinity, chemical composition, optical properties, and residual stress. X-ray diffraction analysis revealed that the film deposited by PLD was amorphous, while PECVD technique yielded crystalline BxC film. PLD technique provided films with better stoichiometric purity with B4C being the most dominant phase, as observed in XPS spectra. However, super-stoichiometric phase (BxC (x > 4)) was dominant in PECVD film. Moreover, the PECVD film had greater adhesion (Lc3 ~29.5 N), hardness (~2798 HK), and lubricity (COF~ 0.03) compared to PLD deposited film. Optically, PECVD deposited film have higher value of refractive indices (1.82 at 600 nm) and lower extinction coefficient. Finally, residual stress measured via substrate curvature method revealed that for PLD 400 C film, the stress was compressive in nature while the same for PECVD -100 V film was tensile, with 10 times less in magnitude. Ultimately, this study provides the user with opportunity to weigh the advantages and disadvantages of PECVD and PLD techniques for deposition of functional BxC films.