JOURNAL OF LUMINESCENCE ELSEVIER Journal of Luminescence 76&77 ( 1998) 306-309 Near-field Raman spectroscopy of semiconductor heterostructures and CVD-diamond layers M. Goetz, D. Drews, D.R.T. Zahn, R. Wannemacher” Institute of Physics, Technical Unicersig of‘ Chemnitz, D-N107 Chemnk Germunv Abstract Raman scattering from semiconductor surfaces as well as from bulk and CVD diamond samples has been detected with high spatial resolution using a near-field optical microscope operating in the detection mode. First- and second- order near-resonant Raman scattering involving the 250 cm- ’ longitudinal optical (LO) phonon of ZnSe in an epitaxial ZnSe layer on GaAs has been studied in the vicinity of the heterointerface. CVD diamond samples were investigated using the near field as well as a conventional optical microscope. A positional dependence of the scattering from diamond and graphitic carbon has been found in the near-field experiments. &y, 1998 Elsevier Science B.V. All rights reserved. Keywords: Near-field optical microscopy; Raman spectroscopy; ZnSe; CVD diamond The development of the scanning near-field optical microscope (SNOM) [I] has led to sub- wavelength resolution in optical microscopy and offers the additional advantage of a simultaneous topographic image of the sample surface. Spatially resolved information about the chemical nature of the sample can be obtained by combining the SNOM with optical spectroscopies, such as fluores- cence [2] or Raman spectroscopy [3]. In addition, artifacts [4] due to coupling to the z-movement of the tip in shear-force control are clearly eliminated by resolving the spectral content of the optical signal at each point of the scan range (such arti- facts, however, still need consideration, if only one spectral component of the light is registered during the scan, such as in Ref. [3]). Due to the very low *Corresponding author. Tel.: + 49 371 531 3009: fax: + 49 371 531 2692; e-mail: wannemacher@physik.tu-chemnitz. Raman scattering efficiency only few studies involv- ing Raman scattering experiments with a SNOM have been reported so far (see, e.g. Ref. [3,5-91. In one of the first studies [3] uncoated tips were em- ployed in order to obtain sufficiently strong signals. In this case, however, spatial resolution is not im- proved over that of conventional optical micro- scopes. A significant step forward was the report of Raman imaging of Rb-doped KTiOP04 samples using a SNOM with a metal-coated glass fiber tip by Jahnke et al. [3]. Here we give a preliminary report of Raman scattering experiments on semi- conductor heterostructures as well as bulk and CVD diamond samples. The SNOM used for our studies was homebuilt and employs conventional optical shear-force con- trol with a 670 nm diode laser. The piezo scanner and dither tubes were arranged opposite to each other, allowing convenient access to the sample from the top. The SNOM was mounted on a vibra- tion isolation table, and a plastic hood helped to 0022-2313/98/$19.00 ,(_‘ 1998 Elsevier Science R.V. All rights reserved PII SOO22-2313(97)00217-2