Crystalline and electrical characteristics of C60 uniformly doped GaAs layers

Abstract

C60 uniformly doped GaAs and C60, Si codoped GaAs layers are grown on GaAs substrates by a migration enhanced epitaxy method. X-ray diffraction measurements indicate that the crystalline quality of the C60 doped GaAs layers is not deteriorated until the concentrations of 1×1019cm−3. In high-resolution transmission electron microscopy images, dark spots induced by the strain contrast are observed in C60 uniformly doped GaAs layer and no dislocation is confirmed around the doped C60 molecules. The electron energy-loss spectroscopy spectrum at the C60 rich region coincides well with the results of pure C60 crystals, indicating that unoccupied molecular orbitals of the C60 molecules are active even in the GaAs lattices. Raman scattering peaks from C60 molecules are obtained for the layers with high C60 concentrations. At low temperatures, the photoconductivity peak around 1000nm appears only in the C60 doped GaAs layers, implying that the resonant excitation between C60 traps and GaAs bands occur.