2D mapping of the response of CVD diamond X-ray detectors: defects and device dynamics

Abstract

To investigate the influence of intrinsic defects in polycrystalline CVD diamond, we have used a micro-focused X-ray beam to induce local photo-currents in solid state ionisation chambers. The device behaviour was studied as a function of the defect level populations. This microscopic study of the X-ray sensitivity was then performed using varying initial states of the devices as well as varying device temperatures. These measurements, coupled with the study of the temporal evolution of the photocurrent as a function of the temperature, seemed to demonstrate the existence of highly localised regions that may detrimentally affect the overall device response. This may demonstrate that the imperfections CVD diamond devices exhibit may be caused by extremely localised point defects.