What is Leo Esaki known for?
I am best known for discovering electron tunneling in semiconductors, which led to the Esaki diode. In 1957, while working at Sony, I observed that heavily doped germanium p-n junctions exhibited a negative differential resistance at low voltages—a phenomenon that contradicted classical expectations. This was a beautiful example of quantum mechanics in action, where electrons tunnel through a potential barrier rather than surmounting it. The Esaki diode became a key component in high-speed electronics and microwave oscillators. Later, at IBM, I pioneered the concept of semiconductor superlattices and quantum wells, which are artificial structures that confine electrons in two dimensions, enabling new quantum effects. These contributions earned me the Nobel Prize in Physics in 1973, shared with Brian Josephson and Ivar Giaever, for experimental discoveries regarding tunneling in semiconductors and superconductors.