Electrical, crystallographic, and optical properties of ArF laser modified diamond surfaces

Abstract

Pulses of 193 nm radiation from an ArF laser with energies exceeding 0.5 J/cm² have been shown to modify 40–60 nm thick layers of {100} and {110} oriented diamond surfaces. These layers exhibit highly anisotropic electrical and optical properties which have principal in‐plane axes along the 〈110〉 directions. The minimum resistance is (4–10)×10⁻⁴ Ω cm, and minimum in the optical transmittance and maximum in the reflectance occur when the electric field vector of the incident polarized light is aligned along the low resistance direction. Transmission electron microscopy indicates that the modified layer primarily consists of unidentified graphite‐like carbon phases embedded in diamond. The first‐order electron diffraction spots correspond to lattice spacings of 0.123, 0.305, and 0.334 nm. The modified layer is stable at 1800 °C, forms ohmic contacts to type IIb diamond, and supports epitaxial diamond growth.