Regensburg 2010 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 32: Poster I: Group II - Oxides

HL 32.5: Poster

Dienstag, 23. März 2010, 18:30–20:30, Poster D1

Capacsim - numerical modelling of the capacitance of a current-free Schottky diode — •Matthias Schmidt, Martin Ellguth, Holger v. Wenckstern, Rainer Pickenhain, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Leipzig, Germany

Schottky diodes (SD) are under investigation for more than 50 years and are a powerful tool in semiconductor defects research. A number of different techniques, each of them somehow connected to the capacitance, or more generally the admittance, were established: e.g. capacitance - voltage spectroscopy (CV), thermal admittance spectroscopy (TAS), and photo capacitance (PCAP).

We developed a numerical model to calculate the admittance of a SD. It provides a realistic reproduction of the influence of six independent parameters - the applied bias, the probing voltage and frequency of the capacitance bridge, the temperature, and illumination of the sample, parameterised by the photon flux and the photon energy. The model takes into account the potential distribution at the Schottky barrier which is calculated numerically in the general case. In case of homogeneous doping of the sample, an analytical solution is used. Furthermore, the time evolution of the occupancy of a trap surrounded by an oscillating electron environment is considered and provides information on the contribution of the local trap density to the measured admittance.

Finally exemplary simulations and a comparison with CV, TAS, and PCAP measurements on real zinc oxide Schottky diodes are presented.