OPTICAL QUANTUM-SIZE EFFECTS IN DIAMOND-LIKE CARBON SUPERLATTICE STRUCTURES

Superlattice structures fabricated using high (2.8 eV) and low (1.5 eV ) band gap modulated diamond-like carbon (DLC) thin film layers give e vidence of quantum size effects. The DLC films were deposited using a CH4-Ar gas mixture in a 13.56 MHz r.f. powered plasma enhanced chemica l vapour deposition (PECVD) system under computer control. Glancing an gle X-ray diffraction was used to verify the existence of superlattice potential barriers. X-ray photoelectron spectroscopy data coupled wit h electronic conduction analysis was used to construct an electronic b and diagram for the amorphous DLC superlattice structure. The 'blue sh ift' observed in the optical band gap was examined. Analysis of the in crease in optical band gap with decreasing well width gives an effecti ve mass of 0.067m(0) for the electrons and holes (which are assumed to be equal).