Laser direct writing and doping of diamond-like carbon, polycrystalline diamond, and single crystal silicon carbide

Abstract

Nanosecond pulsed Nd:yttrium–aluminum–garnet laser treatment is applied to alter the electric properties of free standing polycrystalline diamond substrates, diamond-like carbon (DLC), and 4H–SiC single crystal wafers. In the case of DLC samples, the laser irradiation, nitrogen doping, as well as the incorporation of cobalt into the DLC layer reduces its electric resistance. Laser fabrication of Schottky barrier diode at the DLC–cobalt contact is demonstrated, and its nonlinear 1/C2 vs V curve indicates a nonuniform dopant distribution. The nitrogen dopant profile in the laser-doped SiC wafer is obtained by secondary ion mass spectroscopy and the corresponding nitrogen diffusion coefficient under laser processing parameters is calculated. Laser doping enhances the nitrogen diffusivity in SiC and allows in situ fabrication of metal contacts with no additional materials. Scanning electron microscopy, wavelength dispersive spectroscopy, and x-ray photoelectron spectroscopy are used to study the surface composition and the binding states in the laser-treated samples.