Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 48: Preparation and characterization
HL 48.4: Vortrag
Donnerstag, 30. März 2006, 16:00–16:15, POT 151
Static and dynamic capacitance measurements on the nanoscale — •Stefan Jaensch, Christoph Henkel, Heidemarie Schmidt, and Marius Grundmann — Universität Leipzig, Fakultät für Physik und Geowissenschaften, Institut für Experimentelle Physik II, Linnestrasse 5, 04103 Leipzig
Using standard scanning capacitance microscopy (SCM) techniques the voltage derivative of the contact capacitance is measured with a lock-in amplifier and yields the two dimensional concentration profile of free carriers on the nanoscale. The tip-sample contact complicates the quantitative analysis of standard SCM data. Furthermore, due to the used 5-100 kHz lock-in technique, the characterisation of deep defects (emission barrier energy, capture cross section, defect distribution) by capacitance transient measurements in the µs up to s range is impossible. The presented, newly developed scanning probe technique works in the 2-2.5 GHz frequency range and facilitates quantitative temperature dependent static and dynamic capacitance measurements with a sensitivity better than 10−21 F/√Hz in combination with a standard AFM and SCM probes. The method implies frequency tuning of the integrated voltage controlled oscillator around the resonance frequency of the used coaxial resonator without and with tip-sample contact to determine the stray capacitance and the bias and time-dependent tip-sample capacitance, respectively. Assuming a bias and time independent stray capacitance, the measured transfer function of the coaxial resonator yields the static and dynamic capacitance of the sample piece being fixed to the middle pin of the coaxial resonator by an ohmic contact.