Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 9: Poster I
HL 9.46: Poster
Montag, 27. März 2006, 15:15–17:45, P3
Formation of Antimony rich double layer structures at InP/GaAsSb Interfaces — •Stefan Weeke1, Martin Leyer1, Markus Pristovsek1, and Wolfgang Richter2 — 1Institut für Festkörperphysik, Hardenbergstraße 36, TU Berlin, 10623 Berlin — 2Dipartimento di Fisica, Roma II (Tor Vergata), Via della Ricerca Scientifica 1, I-00133 Rome, Italy
The GaAsSb/InP material system is promising for InP based DHBTs. However, segregation of antimony into InP is a serious problem, affecting the quality of the interface and hence the device performance. To investigate the segregation behaviour of antimony, we exposed InP surfaces with antimony by TMSb covering the typical InP/GaAsSb growth temperature range in MOVPE.We have observed the unexpected formation of an antimony rich double layer structure with one layer occuring at the interface and the other 50 to 100nm deep in the InP overlayer after subsequent overgrowth with InP. It was observed that the spacing between the layers depends on growth temperature, growth rate and the amount of antimony deposited on the surface.During MOVPE growth of GaAsSb only the antimony rich surface reconstruction is observed by RAS. During overgrowth with InP the antimony slowly vanishes, until at a certain point all remaining Sb is incorporated into a second antimony rich layer. This transition is most easily seen in first derivative of the RAS transients. As an explanation of this unusual segregation behaviour a model of strain induced surface melting is proposed.