A balanced experimental and theoretical research program in the area of nanometer-scale thermal engineering in electronic materials is planned. Research will be focused on (1) thermal properties, heat generation and transport in sub-micrometer-scale structures; (measurement of temperature and thermal properties at nanometer scales; (3) heat transfer across interfaces. These studies will be carried out on electronic and opto-electronic materials such as silicon, III-V semiconductors like gallium arsenide and its alloys, as well as metals. Typical applications involve high electric fields, leading to non-equilibrium electron energy distributions. Electron-phonon interactions further lead to non-equilibrium phonon interactions. Theoretical/numerical studies will involve the development of Monte Carlo simulation packages for transport of non-equilibrium electrons and phonons. Experimental studies will involve measurements made with the scanning tunneling microscope (STM) and the atomic force microscope (AFM). A technique to use AFM to measure effective lattice and electron temperatures with nanometer resolution will be developed. Studies of the thermoelectric effect associated with heat transport by electron tunneling will also be studied. The studies are of fundamental importance to nanoengineering and may also have applications in the development of nanometer-scale tunneling sensors for temperature and heat flux.