Measurement of Space-Charge-Limited Current Characteristics in High-Resistivity Materials

A method is proposed for the measurement of space-charge-limited current characteristics in high-resistivity materials which overcomes the difficulty of ensuring thermal equilibrium conditions throughout the measurements. Measurements carried out on high-resistivity single crystals of CdS, using this method, show the well-known characteristics of space-charge-limited current. It is shown that if proper care is not taken to ensure thermal equilibrium, the measured I-V characteristics depend strongly on the history of the sample and their interpretation on the basis of space-charge-limited current theories is unjustified and meaningless.