Photoelektrische Messungen mit der Rastersondenmikroskopie zur Mikroanalyse reiner und modifizierter Halbleiteroberflaechen im Elektrolyten Projektabschlussbericht

Abstract

A novel method for measuring the local photocurrent together with the topography on semiconductor samples with a resolution less than 1 nm is described. The setup is based on a scanning tunneling microscope and is especially able to measure the short circuit photocurrent in order to distinguish it from pure photoconductivity. With measurements in ambient environment on a tungsten diselenide model semiconductor it is shown that the system consisting of the tunneling tip, the tunnel gap and the semiconductor behaves as a nanosized MIS (metal-insulator-semiconductor) solar cell. The spatially resolved photocurrent is a quite sensitive tool for analyzing the electronic variations on a semiconductor surface. Variations in flat band potential as well as changes in the recombination rate can be detected and linked to structures of the surface, below the surface, or on metal particle modified surfaces. It is possible to visualize the space charge zones along steps as well as around catalyst particles on the surface. Measuring the photocurrent makes it possible to directly observe effective barriers of copper particles and of size effects influencing the width of the space charge layer at the surface. (orig.)16 refs.SIGLEAvailable from TIB Hannover: RA 831(3718) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekStiftung Volkswagenwerk, Hannover (Germany)DEGerman