Observation of Hopping Conduction in Heavily Boron‐Doped Single‐Crystal Diamond by AC and DC Conductance Measurements

Hopping conduction in boron‐doped single‐crystal diamond is comprehensively investigated using multifrequency admittance spectroscopy. This dynamic method enables extraction of activation energy and carrier emission rates as functions of temperature. In heavily doped samples, hopping conduction appears below 170 K with activation energies of 20–35 meV. For valence band conduction, dominating at higher temperatures, AC measurements yield activation energies on the average 80 meV lower than DC values, the reason is the essential nonequilibrium measurement conditions and the appearance of additional displacement current. A model is developed to quantify impurity band broadening from conductance spectra, revealing Gaussian density of states distribution with 2–6 meV width estimated from the numerical fitting of the experimental data. The AC approach reflects real device conditions and applies to other heavily‐doped semiconductors.