The analysis of defect structures and substrate/film interfaces of diamond thin films

Abstract

Diamond is an excellent candidate material for use in selected electronic and wear resistant coating applications due to its superior hardness, strength and thermal conductivity as well as its high electron drift velocity, chemical and thermal stability, radiation hardness and optical transmission. Electronic devices of particular interest include those having high-power, -frequency and -temperature applications, as well as those for chemically harsh and/or high radiation flux environments. The recent development of techniques for growth of crystalline diamond films at low pressures using common hydrocarbon and H2 gases has created the potential for growing thin films for such devices or wear resistant coatings and a host of related applications. In this research, diamond thin films grown from a low pressure methane-hydrogen gas mixture by microwave plasma enhanced chemical vapor deposition (CVD) have been examined by various transmission electron microscopy (TEM) techniques including bright and dark field, high resolution (HREM), selected area diffraction (SAD) and electron energy loss spectroscopy (EELS). Columnar growth of polycrystalline grain structure, twins, stacking faults, dislocations and intermediate layers were characteristic of the diamond films. No sp2 bonding character in the grains, defects or grain boundaries was detected by EELS.