We discuss the possibilities of analysis of electrically active defects in semiconductors and dielectrics by means of Isothermal Capacitance-Transient Spectroscopy and Isothermal Charge-Transient Spectroscopy, applied on sub-micrometer scale. While the first of them utilizes the relaxation of the depletion layer, caused by emission of trapped charges and requires sufficient conductivity, the second directly integrates the transient current and can be applied also to low-conductivity materials like dielectrics.
We present some results obtained on pentacene thin films. By means of our charge-transient spectrometer we have achieved a resolution of hundreds of electrons but we believe it can be further improved approximately by one order of magnitude. In materials with relatively high defect concentration, using optimal shape of the probe, a resolution on the order of tens of manometers can be achieved. At low defect concentrations, e.g. in device quality silicon, a resolution on the hundred-nm level is expected.