Dresden 2003 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 14: Poster I
HL 14.4: Poster
Montag, 24. März 2003, 17:00–19:30, HSZ/P2
Site Selective Detection of Deep Level Centers by X-ray Absorption Fine Structure ? — •Joachim Bollmann1, Steffen Knack1, Jörg Weber1, Edmund Welter2, Heinz-Eberhard Mahnke3, Vasil Koteski3, and Rainer Sielemann3 — 1Technische Universität Dresden, D-01062 Dresden, Germany — 2HASYLAB, D-22603 Hamburg, Germany — 3HMI, D-14109 Berlin, Germany
Recently, a scheme of capacitance-detection for the X-ray absorption fine structure (XAFS) has been reported which would widely expand the application of XAFS to defect centers with deep electronic states in a semiconductor /1/.
The possibilities and limits of an electrical detection are discussed. Special attention is given to the question whether capacitance EXAFS can selectively detect strongly diluted defects. The XAFS at the K-edge of gallium and arsenic is measured on GaAs and AlGaAs Schottky-diodes containing DX and EL2 defect centers. The X-ray absorption is detected electrically by monitoring (i) the photo-current under short circuit conditions, (ii) the steady state impedance, and (iii) X-ray induced capacitance transients. We do not find any significant differences between the electrical and conventional detected XAFS spectra and the suggested site selectivity is strongly questioned.
/1/ M. Ishii: Phys. Rev. B 65, 085310 (2002).