Characteristics of 2-photon ultraviolet laser etching of diamond

We report graphite-free laser etching of diamond surfaces using 266 nm laser pulses for a wide range of incident fluences below the threshold for ablation. The etching rate is proportional to the (fluence)x where x = 1.88 ± 0.16 over the range 10−6 - 10−2 nm per pulse for incident pulse fluences 1 – 60 J/cm2. Surface sensitive near edge x-ray fine absorption structure measurements (partial electron yield NEXAFS) reveal that etching does not significantly alter the surface structure from the initial oxygen terminated and graphite-free state. The etching process, which is consistent with a mechanism involving the desorption of carbon species via the decay of 2-photon excited excitons near the surface, appears to have no threshold and is promising for creating a range of high resolution structures.