Refractive indices and absorption coefficients of In1−x Gax P1−yAsy for y = 0 to 1 lattice matched to InP and of GaAs and GaP have been measured by ellipsometry in the wavelength range between 365 and 1100 nm. The high-purity layers (7×1014<n<2×1016 cm−3) used here were grown by liquid phase epitaxy. The quaternary refractive indices were also calculated from the measured indices of the constituent binary compounds by averaging the quantity (ε−1)/(ε+2). The ε values were all taken at the same energy separation from the respective band gaps. The results of this new averaging procedure are compared with the measured indices and with the refractive index steps to InP deduced from lasers. In addition, the absorption coefficient of InP near the band gap was measured as a function of the doping level. Finally, the temporal growth of the natural oxide layer thickness dox on various InP and GaAs samples was determined by ellipsometry. For InP, the increase of dox is 0.39 nm per decade of time.

An electron spectrometer consisting of an electron transport system with normal conducting solenoidal coils and a Si(Li)-detector as the energy dispersive element is described. It can be used for in beam spectroscopy of electrons in three different modes. The first one is the usual broad range mode with a low energy cut offofthe transmission performed by a tantalum disk between target and detector. The second one is the lens spectrometer mode. An envelope baffle system permits electron detection in a momentum band A pip = 0.12. To cover a large energy range the magnet current is sweeped. In the third mode-the recoil shadow method -a longitudinal semicylindrical baffle between target and Si(Li)-detector allows spectroscopy of delayed electrons emitted from recoil nuclei in flight. Special features of this method are high transmission, and strong suppression of the prompt 3-electron background. Lifetime measurements based on the detection of conversion electrons are possible by variation of the target position. This was tested with the 152Sm(160, x n) 168 -xyb compound nuclear reaction at a recoil velocity vr = 0.01 c, where half lives between 0.1 ns and 1 ns were determined.

No abstract

No abstract

No abstract