Scanning tunnelling microscopy: application to field electron emission studies

The principles of scanning tunnelling microscopy (STM) are extended to the study of field electron emission from metal, semiconducting and semi-insula ting materials. A specially designed, high-vacuum STM device called a scann ing tunnelling field emission microscope (STFEM) is constructed, and new me asuring procedures are developed to examine complex physical properties of emission centres. Providing high bias voltages and fast mapping of large sq uares, the STFEM allows one to obtain reliable statistical data on surface properties, namely topography, emission intensity, surface potential distri bution and local electroconductivity. Results from a study of low-field ele ctron emission from CVD diamond films are described to illustrate the funct ional capabilities of the new STM device. It was found that the diamond fil ms studied are composed of nanograined phases distinguished by their physic al properties. It has also been noted that the low-field electron emission from the studied samples is associated with the interfaces of these phases.