Dr. Rohatgi has conducted research in the areas of modelling and fabrication of high efficiency silicon solar cells;  materials for high performance photovoltaic and power devices; tandem solar cells using hetrojunctions; fundamental understanding of defects and their passivation in multicrystalline  materials, for low-cost high-performance devices; defects and carrier lifetime limiting mechanisms in semiconductors;  materials and devices for VLSI circuits; optical and electronic properties of compound semiconductors;  MBE and MOCVD growth of III-V and II-VI semiconductors for opto-electronic devices and solar cells; low temperature dielectrics and rapid thermal processing;  and materials characterization and novel instrumentation techniques.