Dresden 2006 – scientific programme
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DS: Dünne Schichten
DS 19: Thin film deposition and process characterization I
DS 19.3: Talk
Thursday, March 30, 2006, 12:00–12:15, GER 38
In situ doping profiling of MOVPE-grown GaAs — •Ch. Kaspari1, M. Pristovsek1, and W. Richter2 — 1Technische Universität Berlin, Institut für Festkörperphysik, Sekr. PN 6-1, Hardenbergstraße 36, D-10623 Berlin — 2Università di Roma Tor Vergata, Dipartimento di Fisica, Via della Ricerca Scientifica 1, I-00133 Roma, Italy
It is well known that doping of III-V-semiconductors can be measured with reflectance anisotropy spectroscopy (RAS) [1]. The interface electric field induced by the dopant atoms changes the RAS spectrum. This change, observed near the E1 and higher critical points, can be described by the linear electro-optic effect (LEO).
We have found that during growth of GaAs layers with different doping concentrations, oscillations appear in the RAS signal at photon energies near the fundamental band gap E0. From the period of these oscillations the thickness can be obtained during growth. The amplitude of the oscillations is related to the doping contrast. With this information, a profile of the doping concentration can be measured in situ. To refine the accuracy of our measurements, we employ a multichannel RAS setup [2] that is designed to measure transients at multiple photon energies simultaneously in the spectral range between 1.5 and 5 eV.
[1] Tanaka et al., Appl. Phys. Lett. 59, 3443 (1991)
[2] Kaspari et al., phys. stat. sol. (b) 242, 2561 (2005)