Electronic and ionic charge carriers in irradiated single crystal and fused quartz

The charge carrier transport properties of a wide variety of quartz single crystals and fused silica have been measured by creating electron-hole pairs in the bulk of the samples with high energy x-rays. The very short x-ray pulses (3 nsec) allowed unprecedented time resolution, and in some cases separate measurements of carrier concentration, (α) lifetime, (tau) and mobility, (μ) as well as their product (αeμtau). The αeμtau product is sometimes called the radiation induced conductivity (RIC) and was found to vary over almost four orders of magnitude for different types of quartz. In addition, substantial long term conductivity was discovered in some kinds of single crystal quartz with the electric field parallel with the c-axis. It is concluded from the available evidence that the long lived carriers are alkali metal ions which can be drifted across the entire crystal. The possible origin of the ions is discussed as well as their role in the short term annealing of the radiation-induced frequency offsets noted in quartz oscillators. (author)