Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 48: Poster 2
HL 48.91: Poster
Donnerstag, 26. März 2009, 15:00–17:30, P2
Barrier height measurements of InxAl1−xN — •Christian Barth, Mareike Trunk, and Daniel M. Schaadt — Institut für Angewandte Physik, Universität Karlsruhe (TH), and DFG Center for Functional Nanostructures, CFN, D-76128 Karlsruhe
InN - metal contacts show no Schottky barrier due to Fermi level pinning in the conduction band. AlN - metal contacts however form Schottky barriers. By changing the In to Al ratio, the barrier height could be adjusted over a large range. However, it also known that InAlN shows the tendency to demix into InN and AlN and that it is therefore difficult to obtain high quality films. The defects will likely decrease the ideality of the contact. Therefore barrier height measurements require a robust setup which can cope with non ideal diodes. By performing capacitance - voltage measurements at different frequencies, we can obtain the series resistance (spreading resistance) and parallel resistance (due to leakage paths along defects) for non-ideal diodes. Incorporating these parameters in a combined model, reliable barrier height extraction with little temperature dependence is possible. The setup consists of a LCR-meter and a linear power supply which are controlled from a measurement program. This program allows voltage and frequency dependant measurements and directly calculates the barrier height. A verification of this method with measurements on known barrier heights of Au on Si and GaAs as well as results for InxAl1−xN is presented