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.

Theoretical models for doping diamond for semiconductor applications

“…The presence of boron-pairs and boron-vacancy complexes may contribute to the reported reduction in doping efficiency in heavily doped diamond [88]. For example, although V-B 3 may have a shallow acceptor level, it will only contribute one hole for three boron impurities, i.e.…”

Thermoelectric transport properties of boron-doped nanocrystalline diamond foils

“…In the case of doping high-pressure, high-temperature diamond with boron, the dopant tends to accumulate in the grain boundaries, and it has been hypothesized that superconductivity arises from intergranular boron-rich material [33]. In particular, segregation of boron is expected when its amount exceeds 5 · 10 20 cm À3 , the limit for substitution of carbon in the diamond lattice [34].…”

“…This ideal situation is represented by the leftmost dashed line with a slope equal to unity. The charge carrier concentration is assumed to become constant when the solubility limit (0.28 at% [34]) is reached and excess boron may take interstitial positions or precipitate into foreign phases depending on the conditions during the deposition process.…”

Room temperature DC magnetron sputtering deposition and field emission of Al‐doped ZnO films

“…However, since the electron density is small, the number of electrons having enough energy to overcome the barrier is still small and this results in small emission current density. The defects in ZnO:Al might form energy bands within the forbidden band gap of ZnO:Al 30–32 and this possibly accounts for the nonlinearity of the FN curves in Fig. 5(b).…”