Fast digital apparatus for capacitance transient analysis

• Published in: Review of scientific instruments 1980-09, Vol.51 (9), p.1205-1211
• Main Authors: Wagner, Elmar E., Hiller, Don, Mars, Dan E.
• Format: Article
• Language: English
• ISSN: 0034-6748; 1089-7623
• DOI: 10.1063/1.1136396

The analysis of transient phenomena originating from relaxation processes is a tool for material and device characterization. The time constants of the transients provide information about the energy levels involved, and the transient amplitude is coupled to the density of occupied states. A convenient method for the analysis of exponential transients is the use of correlation‐spectroscopic techniques. An example is deep level transient spectroscopy, a capacitance method for the study of deep impurities in semiconductors. The correlation with a weighting function is in this case conventionally made by hardwired instruments. We demonstrate here how shortcomings of this method can be avoided and higher flexibility can be achieved by separating the signal processing from the data acquisition. The hardware is a high‐resolution capacitance measurement system with a resolution of 0.002 pF in capacitance and 5 μs in time. As a result of the measurement, which is considerably faster than analog methods, a data array describes the response of the sample with regard to time and temperature. Several signal processing routines are applied to the data to filter out specific information.