Electrical and structural characterization of carbon based films prepared by RF-PECVD and ECR-PECVD techniques for photovoltaic applications

Carbon based materials, such as amorphous carbon (a-C) and hydrogenated amorphous carbon (a-C:H) as well as diamond like carbon (DLC) with predomination of sp(3) bonds are widely used in electronics and machinery. Among other advantages of these materials, environmental friendly method of preparation is important. In the field of photovoltaics (PV) they can be used as antireflective coating or as emitter layer in amorphous carbon/crystalline silicon (a-C/c-Si) heterojunction for low cost solar cell structure. Diamond-like carbon film was deposited on p-type Si (100) substrates at various deposition conditions by means of Radio Frequency Plasma-Enhanced Chemical Vapor Deposition (RF-PECVD) and Electron Cyclotron Resonance Plasma-Enhanced Chemical Vapor Deposition (ECR-PECVD) techniques. The concentration of chemical elements in films was determined by both, Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERD) analytical method. RBS and ERD analysis indicate that the films contain carbon, hydrogen and a small amount of oxygen. The current transport mechanisms in prepared samples were investigated using analysis of current-voltage (I-V) and capacitance-voltage (C-V) measurements.