TEMPERATURE-DEPENDENCE OF THE INP(001) BULK AND SURFACE DIELECTRIC FUNCTION

The bulk dielectric function, the surface reflectance anisotropy, and the surface dielectric anisotropy of InP(001) were determined from roo m temperature up to 875 K. Measurements were performed in-situ on as-g rown samples in both a metal-organic vapour phase epitaxy and a chemic al beam epitaxy (CBE) system using a rotating analyser type ellipsomet er (SE) and a reflectance anisotropy spectrometer (RAS). The temperatu re dependence of the bulk critical points was deduced by performing a direct line shape analysis of the SE spectra. A high-temperature bulk dielectric function database for optical in-situ studies was establish ed by applying a combined cubic spline/harmonic oscillator interpolati on scheme to the measured data. Three InP(001) surface reconstructions were found by reflection high-energy electron diffraction (RHEED) mea surements in the CBE system: (2 x 1) and c(4 x 4) under phosphorus-ric h conditions and a (2 x 4) reconstruction under reduced phosphorus sup ply. Characteristic RAS spectra are assigned to these reconstructions. The temperature shift of the main features of the surface dielectric anisotropy spectra are compared to those of the bulk critical points.