He worked in a number of research laboratories in Germany and the Unites States and taught electrical engineering at the University of Colorado from 1968 to 1976. He joined the UCSB faculty in 1976, focussing its semiconductor research program on the emerging compound semiconductor technology rather than on mainstream silicon technology.
Kroemer, a member of the National Academy of Engineering, has always preferred to work on problems that are ahead of mainstream technology. In the 1950s, he was the first to point out that advantages could be gained in various semiconductor devices by incorporating heterojunctions into the devices. Most notably, in 1963 he proposed the concept of the double-heterostructure laser, the central concept in the field of semiconductor lasers. Kroemer became an early pioneer in molecular beam epitaxy, concentrating on applying the technology to untried new materials.