A novel STM-based depth profiling technique for the electronic characterisation of thin film materials

Material removal from a sample surface by operating a scanning tunneling mi croscope (STM) in the scanning tunneling spectroscopy (STS) mode can be con trolled at the rate of a few angstroms per bias voltage ramping cycle. Moni toring the modified sample surface by tunneling spectroscopy allows determi nation of the electronic properties of the material. By combining these two capabilities, a novel type of depth profiling based on surface electronic properties has been proposed and studied. This depth profiling technique is based on the removal of small amounts of material obtained by operating th e STM in the surface modification mode while simultaneously acquiring tunne ling spectra from the material revealed by the tunneling electrons. The I-V curve profile is monitored on a pulse-by-pulse basis which allows the corr elation of electronic properties with the etching depth. By this technique, the surface damage on the baron ion-implanted CVD diamond films and argon ion-etched CVD diamond films has been investigated. It has also been demons trated that this technique can be used to measure thin film thickness. It i s envisaged that this experimental technique could find applications in the characterisation of shallow-doped semiconductor devices. (C) 2000 Elsevier Science B.V. All rights reserved.