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In 1952, Herbert Kroemer received his Ph.D. degree from the University of Göttingen, Germany, with a thesis titled "Über eine neue Art der Halbleiterverstärkung" ("On a new type of semiconductor amplification"), under the supervision of Nobel laureate Werner Heisenberg. His pioneering work laid the foundation for the development of heterojunction bipolar transistors and contributed significantly to the field of semiconductor physics.