Z.-H. Huang

THEORETICAL STUDY OF FIELD EMISSION FROM DIAMOND

The electron field emission from diamond surfaces is investigated theoretically using a model consisting of the projection of the energy band surfaces in the 〈111〉, 〈110〉, and 〈100〉 emission directions. The effect of the negative electron affinity, the band bending, the image interaction, and surface states is examined in detail. It is found that the conventional theory of electron field emission applied to crystalline diamond cannot explain the measured high‐current emission at low fields. We postulate two subbands in the intrinsic band gap, which may be generated by defects or impurities. With reasonable band parameters, the calculated I‐V characteristics agree with experimental data.

Monte Carlo simulation of hot electron charge transport in diamond under an internal electric field

Charge transport in diamond is studied using the Monte Carlo method, in which the scattering of electrons by phonons is considered stochastically. It is assumed that electrons are injected into the diamond conduction band with an initial equilibrium energy distribution and they are then accelerated by the internal field subject to phonon scattering. It is found that the electron energy distribution is independent of the field up to ≂0.1 V/μm. For larger fields, ‘‘hot’’ electron transport is predicted, i.e., the distribution shows a tail which depends on the internal field and the thickness of the diamond film. It implies that if electron field emission is from the conduction band in a diamond film, the transport and the energy spectrum of the emitted electrons should exhibit hot electron features.

Computer simulation of a wave packet tunneling through a square barrier

It is shown that, for energies E<or=V/sub 0/, the barrier height, the typical tunneling time is on the order of 10/sup -15/ s. The traversal time as a function of kinetic energy is locally symmetric near E=V/sub 0/. The tunneling time depends on the shape of the wave packet. The tunneling time is linearly dependent on barrier thickness for a wave packet with finite width. These conclusions are compared with the results obtained from other methods for estimating tunneling times.

Calculation of electronic properties of defects in diamond: application to electron emission

Electron field emission from diamond has been known experimentally to yield large currents at low fields. It has been speculated that electron transport through band gap states can be responsible for sustaining such currents. These band gap states may be generated by defects such as vacancies and grain boundaries in CVD diamond films. In this paper the electronic structure of single vacancy defects and H-substitutional single vacancy defects is examined using a tight binding model.