Defect-enhanced electron field emission from chemical vapor deposited diamond

Abstract

Diamond samples with varying defect densities have been synthesized by chemical vapor deposition, and their field emission characteristics have been investigated. Vacuum electron field emission measurements indicate that the threshold electric field required to generate sufficient emission current densities for flat panel display applications (≳10 mA/cm²) can be significantly reduced when the diamond is grown so as to contain a substantial number of structural defects. The defective diamond has a Raman spectrum with a broadened peak at 1332 cm⁻¹ with a full width at half maximum (FWHM) of 7–11 cm⁻¹. We establish a strong correlation between the field required for emission and the FWHM of the diamond peak. The threshold fields are typically less than 50 V/μm and can reach as low as 30 V/μm for diamond with a FWHM greater than 8.5 cm⁻¹. It is believed that the defects create additional energy bands within the band gap of diamond and thus contribute electrons for emission at low electric fields.