Dresden 2017 – wissenschaftliches Programm
DS 32.4: Vortrag
Mittwoch, 22. März 2017, 16:00–16:15, CHE 89
Localized defect states and charge trapping in Al2O3 films prepared by atomic layer deposition — •Karsten Henkel, Malgorzata Kot, and Dieter Schmeißer — BTU Cottbus-Senftenberg, Angewandte Physik-Sensorik, K.-Wachsmann-Allee 17, 03046 Cottbus, Germany
The evaluation of the electronic structure and intrinsic defect mechanisms in Al2O3 thin films is essential for their effective use in applications with desired functionality such as surface passivation schemes for solar cells . We present a comparative study of different Al2O3 films grown by atomic layer deposition (ALD) . The layers were deposited on different substrates using the same aluminum precursor (TMA, trimethylalumium) and employing different process parameters (thermal-ALD, plasma-enhanced-ALD, substrate temperature). These films were characterized by resonant photoelectron spectroscopy and by electrical measurements (capacitance-voltage). For all films investigated intrinsic defect states within the electronic band gap were observed including excitonic, polaronic, and charge-transfer defect states, where their relative abundance is subject of the choice of ALD parameters and of the used substrate. The spectroscopic assigned in-gap defect states are related with electronic charges as determined in the electrical measurements.  G. Dingemans and W.M.M. Kessels, J. Vac. Sci. Technol. A 30, 040802 (2012).  K. Henkel, M. Kot, D. Schmeißer, J. Vac. Sci. Technol. A 35, (2017), accepted.