Defect structure and electron field-emission properties of boron-doped diamond films

Abstract

The correlation between electron field-emission properties of diamond films prepared by the chemical vapor deposition (CVD) process and the defect structure induced by boron doping was examined. Secondary ion mass spectroscopic analysis indicates that the solubility limit of boron in diamond is (B3+)2=5×1021 cm−3, whereas the infrared absorption (IR) spectroscopic analysis reveals that the largest boron concentration that can be incorporated as substitutional dopants is only one tenth of the solubility limit, (B3+)d=5×1020 cm−3. Including boron species higher than this concentration induces large strain and atomic defects, which are inferred by the distorted Raman resonance peak, noisy IR spectra, and twinned microstructure for diamond. Presumably, the presence of atomic defects, which behave as electron traps, is the mechanism deteriorating the electron field-emission properties of CVD diamonds.