Optical and electrical effects of radiation damage in diamond

Abstract

Measurements have been made of the optical absorption induced in diamond by irradiation with electrons of energy in the range 0.3 to 2.0 MeV. Rate curves have been determined for various features in the absorption spectrum.Electron irradiation of semiconducting diamond causes a decrease in the resistivity, most of which arises from a decrease in the carrier concentration. The shape of the rate curve of carrier concentration as a function of dose can be satisfactorily explained in terms of radiation-induced donor levels. The variation with electron energy of the rate of introduction of the donor levels has also been determined.Both optical and electrical rate curves are compared with calculated curves for the displacement of atoms, assuming various values of the displacement energy. Up to 1.0 MeV, the optical results have similar shape to the curve calculated for Ed = 80 eV and the calculated number of defects deduced is in reasonable agreement with the concentration of donor levels from the electrical measurements.

Optical absorption and luminescence in diamond

“…The strength of the GR1 band is linearly related to the irradiation dose (Clark et al 1956a(Clark et al , 1961. This indicates an intrinsic lattice defect-no impurity is involved.…”

“…Hence the picture is somewhat ambiguous at present; it may be that the defect can be either a donor or an acceptor, depending on the Fermi level, like the vacancy in silicon (Watkins 1965). Clark et al (1961) deduced for diamond a displacement energy (i.e. the energy needed to displace a lattice atom from its site) of 80 eV.…”

“…Hence it is usually assumed that the GR1 centre is a donor and compensates the acceptors (Wedepohl 1957b, Clark et al 1961, Dyer and Ferdinand0 1966see also $3.2 …”

Development of nanostructured carbon thin films

“…sp 3 percentage will increase if there is a preferential displacement of sp 2 sites. Lifshitz used the displacement threshold of 25 and 80 eV for sp 2 and sp 3 bonded carbon proposed by Kelly [90] and Clark [91] respectively. However, more recent direct measurements of displacement thresholds show similar values for displacement of sp 2 and sp 3 bonded atoms (~ 35 eV) [92][93][94].…”

Development of a novel filtered cathodic vacuum arc deposition system for carbon metal nanocluster thin films

“…The sp 3 percentage will increase if there is a preferential displacement of sp 2 sites. Lifshitz used the displacement threshold of 25 and 80 eV for sp2 and sp 3 bonded carbon proposed by Kelly[70] and Clark[71] respectively. However,…”