Dynamics of electron scattering between bulk states and the C1 surface state of InP(100)

Hot electron dynamics was investigated, with a focus on scattering between bulk states and the C₁ surface state that is formed on the (2×4)-reconstructed In-rich surface of InP(100). The latter surface was prepared via metal organic chemical vapor deposition (MOCVD) and monitored by reflectance anisotropy spectroscopy (RAS/RDS). Two-color twophoton photoemission (2PPE) was employed with laser pulses of about 50 fs duration. Hot electrons were generated in bulk states about 0.5 eV above the C₁ surface state, thereby avoiding any significant direct optical population of the surface state. A time constant of 35 fs was determined from the experimental data for electron scattering from isoenergetic bulk states to the C₁ surface state by analyzing the rise of a C₁-specific peak in the 2PPE spectrum. The decay of this C₁ peak was ascribed to energy relaxation of the photo-generated electrons to bulk states below the surface state. Analogous measurements were carried out with a (2×1/2×2)-reconstructed P-rich surface of InP(100) that was also grown via MOCVD. No sign of a surface statewas detected in the 2PPE spectra for the latter surface in the corresponding energy range of the conduction band. PACS 73.20.-r; 78.47.+p; 79.60.-i; 79.60.Bm