The modulation of electrical carrier transport in metal-MPCVD diamond due to the microcrystalline inhomogeneous barriers

In the present work, we successfully related the macroscopic electrical transport to the microscopic inhomogeneities of the diamond film. A set of MPCVD diamond Schottky devices shows two distinct Schottky Barrier Heights (SBH), one near 1.1 V (dispersion≈0.15 V) and other near 0.2 V (dispersion≈0.02 V). Two activation energies were found: one near 150 meV (high temperature ionization region) and a very low activation energy near 2 meV (low temperature region, due to hopping effects). The study of the bulk conduction shows some evidence of space charge limited conduction influenced by shallow trap levels, as shown by the differential conductivity analysis. A discussion about a Poole-Frenkel model is included. The calculated macroscopic electrical current is obtained and the correlation with the physical structure is made.