A method was proposed for the monitoring of the energy distributions of defects, in the band-gap of a semiconductor, by measuring the complex admittance of a junction. This involved the calculation of the derivative of the junction capacitance with respect to the angular frequency of the alternating current. The signal was corrected by incorporating a factor which took account of band-bending and of the decrease in the alternating current signal over the space-charge region of the junction. The use of numerical modelling demonstrated that energy distributions of the defects could be very accurately reconstructed by using this method. The defect distributions in polycrystalline thin films of the present material were thus deduced from temperature-dependent admittance measurements of heterojunctions.

T.Walter, R.Herberholz, C.Müller, H.W.Schock: Journal of Applied Physics, 1996, 80[8], 4411-20