Thermovoltage imaging using scanning tunnelling microscope was used to observe atomic-scale surface imperfections at room temperature. Thermovoltage mapping could provide high resolution (down to 1nm) images of standing waves in metal at room temperature, thus avoiding the need for low temperature scanning tunnelling microscopy for the investigation of the standing waves. In order to generate a thermovoltage between the sample and tip, the sample (Au(111)) was heated to about 40C above the room temperature and surface scanning was performed. Heating the sample was simpler than heating the tip by laser irradiation. The thermovoltage technique could be applied to estimate surface defect density and the severity of the surface defects in materials, which could be a useful tool for the reliability study of nano-scale materials and devices.

Room Temperature Observation of Point Defect on Gold Surface using Thermovoltage Mapping. A.Roy, C.M.Tan, S.J.O’Shea, K.Hippalgaonkar, W.Hofbauer: Microelectronics Reliability, 2007, 47[9-11], 1580-4