Problems of the point-contact transistor: The point-contact transistor is a surface-effect device, i. e. important effects occur at the semiconductor surface Surfaces are easily contaminated Surface-effect devices are unstable(e. g. mechanical vibrations Remedy William shockley invented the pn- junction transistor The physically relevant region is moved to the bulk of the material The p-n junction transistor is a bulk device Shockley bardeen and brattain were awarded the nobel prize in 1956 OE F Schubert, Rensselaer Polytechnic Institute, 2003© E. F. Schubert, Rensselaer Polytechnic Institute, 2003 11 Problems of the point-contact transistor: The point-contact transistor is a surface-effect device, i. e. important effects occur at the semiconductor surface. Surfaces are easily contaminated. Surface-effect devices are unstable (e. g. mechanical vibrations). Remedy: William Shockley invented the pn-junction transistor. The physically relevant region is moved to the bulk of the material. The p-n junction transistor is a bulk device. Shockley, Bardeen, and Brattain were awarded the Nobel Prize in 1956