An apparatus is described here in detail for the transfer of a sample from a metalorganic chemical vapor deposition ͑MOCVD͒ reactor to an ultrahigh-vacuum ͑UHV͒ chamber without introducing any contamination. The surface of the sample does not change during transfer as is borne out by the identical reflectance difference ͑RD͒ spectrum measured first in the MOCVD reactor, i.e., in situ, and afterwards again in the UHV chamber. Making use of the earlier apparatus a semiconductor can be grown in the MOCVD reactor and can afterwards be investigated with any desired tool of surface science, in particular also those that require UHV. All the data collected in UHV can be identified with the RD spectrum measured already in the MOCVD reactor. Several examples are presented here for data collection in UHV on III-V semiconductors grown in the MOCVD reactor. They illustrate the ease and reliability of the here described apparatus for contamination-free sample transfer. Signals are presented in particular for the genuine MOCVD-grown P-rich seemingly (2 ϫ1)/(2ϫ2)InP(100) reconstructed surface that until now can only be investigated in UHV if one makes use of the sample transfer system described in this article.

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Time-dependent two-photon photoemission spectra are used to resolve the femtosecond dynamics of hot electrons at the energetically lowest surface resonance of reconstructed InP(100). Two different cases are studied, where electrons either are lifted into the surface resonance via a direct optical transition or are captured from bulk states. These data are the first of this kind recorded with a time resolution below 70 fs. The microscopic analysis shows that electron-phonon scattering is a major mechanism for electron transfer between surface and bulk states.