Characterization of semiconductor interfaces with atomic scale resolution by luminescence

Abstract

Luminescence experiments provide a unique powerful and nondestructive approach for the ex situ investigation of semiconductor heterointerfaces. Detailed analysis of the spontaneous radiative recombination in quantum well (QW) structures, i.e. luminescence lineshape analysis, and determination of excitation density and temperature dependence enable quantitative characterization of the structural, chemical and electronic properties of the interfaces on atomic scale. A novel experimental approach, Cathodoluminescence Wavelength Imaging, which involves recording of a complete CL spectrum at every scanning position, yields direct 3D images of the atomic scale morphology of the interfaces as sensed by the QW exciton: similar to the tip of a scanning tunnelling microscope, the QW exciton samples the roughness induced local fluctuations of the QW thickness L z and performs a transformation of this structural information L z (x, y) into a spectral one, the lateral variation of the emission wavelength λ(x, y). By combining the different luminescence techniques interface roughness can be investigated within a space frequency range from (1mm)−1 up to the (nm)−1 regime.