ANALYSIS OF NANOSTRUCTURES BY MEANS OF AUGER ELECTRON SPECTROSCOPY
Gernot Ecke - Volker Cimalla - Katja Tonisch - Vadim Lebedev - Henry Romanus - Oliver Ambacher - Jozef Liday
In modern nanotechnology analysis such methods are needed which are able to investigate extremely small volumes, thus surface sensitive techniques with a high spatial and depth resolution. Concerning the capability of high lateral and depth resolution, Auger electron spectroscopy (AES) is one of the outstanding analytical methods for nanotechnology. By field electron guns probe diameters below $10\,$nm are reached. Depth resolution of Auger electron spectroscopy, depending on the kinetic energy of the Auger electrons, is approximately 0.5 to 4 nm. Whereas large area AES has a detection limit of 0.1 at% it impairs for laterally highly resolved measurements. The article will give some examples for the application of Auger electron spectroscopy to nanostructures mostly in group III-nitride semiconductor technologies: (i)~nanowires, consisting of Si and AlN with diameters of about 20 to 200 nm; these nanowires and nanorods have been grown by different technologies and some of them are contacted on both ends by FIB grown Pt contacts, (ii)~ nanoflowers,ie specially shaped up to 5 &mm sized networks of AlN nanowires of about 20 nm in diameter, (iii)~segregation structures of Si of 200 nm width, grown during PIMBE AlN epitaxy on Si substrate. On the basis of these measurements the benefits and limits of Auger electron spectroscopy on nanostructures as well as some special effects which are characteristic especially for nanostructures, for instance resputtering and background signal contribution, are discussed.
Keywords: nanotechnology, Auger electron spectroscopy, nanowires, nanoflowers, segregation