His research has focused on semiconductor surfaces, interfaces, and processes, including epitaxial thin film growth, silicide formation, phase transitions, quantum dot and nanowire formation, thermodynamics, etcetera. He has developed a number of advanced experimental techniques, including spectroscopic STM, Low Energy Electron Microscopy, In-situ Transmission Electron Microscopy, and others. Tromp has published about 260 refereed papers, several book chapters, and 22 United States Patents.