<P> The effects of semiconductor doping were long known empirically in such devices as crystal radio detectors and selenium rectifiers . For instance, in 1885 Shelford Bidwell, and in 1930 the German scientist Bernhard Gudden, each independently reported that the properties of semiconductors were due to the impurities contained within them . The doping process was formally first developed by John Robert Woodyard working at Sperry Gyroscope Company during World War II, with a US Patent issued in 1950 . The demands of his work on radar denied Woodyard the opportunity to pursue research on semiconductor doping . </P> <P> Similar work was performed at Bell Labs by Gordon K. Teal and Morgan Sparks, with a US Patent issued in 1953 . </P> <P> Woodyard's prior patent proved the grounds of extensive litigation by Sperry Rand . </P> <P> The concentration of dopant affects many electrical properties . Most important is the material's charge carrier concentration . In an intrinsic semiconductor under thermal equilibrium, the concentrations of electrons and holes are equivalent . That is, </P>

What is the effect of doping in semiconductor