Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 26: II-VI semiconductors II
HL 26.3: Vortrag
Dienstag, 28. März 2006, 15:45–16:00, POT 51
Alloy Fluctuations and Phase separation in ZnCdO Layers: Thermalization and Carrier Freeze Out — •Alexander Franke1, Thomas Hempel1, Silke Petzold1, Frank Bertram1, Jürgen Christen1, R. Kling2, Christoph Kirchner2, and Andreas Waag3 — 1Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany — 2Department of Semiconductor Physics, Ulm University, Germany — 3Department of Semiconductor Technology, Braunschweig Technical University, Germany
An inherent problem for the epitaxial growth ZnCdO is a different crystallization of ZnO and CdO into wurtzite and rock-salt structure, respectively resulting in local stoichiometry fluctuation and decomposition up to phase separation. A series of MOCVD grown Zn1−xCdxO layers with systematically increasing Cd-content (0.3%–2.0%) were analyzed using photoluminescence spectroscopy (PL). A systematic red-shift (3.239eV–3.150eV) and broadening of the PL peak is observed with increasing [Cd] merging into a splitting into two well distinguished peaks. While the high energetic main PL peak (dominant Cd-concentration) shows a linear excitation density dependence over more than 4 orders of magnitude, a super-linear dependence is found for the evolving satellite peak (minor Cd-rich local phase). The temperature dependence exhibits a pronounced s-shape behavior of the peak energy characteristic for thermalization and freeze out of the carriers in local potential fluctuations. The PL results are compared with highly spatially resolved cathodoluminescence directly visualizing the Cd-fluctuations and the phase separation.