Injection and accumulation of electric charge in MgO single crystals

We describe the space charge dynamics in MgO single crystals under high voltage at room temperature. The space charge profiles are measured in a nondestructive way using light induced pressure pulses. The build up of a positive space charge near the anode and of a negative space charge near the cathode are observed. The amplitude and extension of these charges depend on the electrode materials. Hole and electron injections at the interfaces can explain the charge distributions observed. (C) 2002 American Institute of Physics.