Negative electron mobility in diamond

By measuring the drift velocity of electrons in diamond as a function of applied electric field, we demonstrate that ultra-pure diamond exhibits negative differential electron mobility in the 100 direction below 140 K. Negative electron mobility is normally associated with III–V or II–VI semiconductors with an energy difference between different conduction band valleys. The observation of negative mobility in diamond, an elemental group IV semiconductor, is explained in terms of repopulation effects between different equivalent conduction band valleys using a model based on the Boltzmann equation.