A point-contact transistor was the first type of solid-state electronic transistor ever constructed, using germanium (a semiconductor) and gold for point-contacts. It was developed by research scientists at Bell Laboratories this date in 1947. The group had been working together on experiments and theories of electric field effects in solid-state materials, with the aim of replacing vacuum tubes with a smaller, less power-consuming device. The point-contact transistor was commercialized and sold by Western Electric and others, but was soon superseded by the bipolar junction transistor, which was easier to manufacture and more rugged. Germanium was employed extensively for two decades in the manufacture of transistors, but was then almost totally replaced by silicon and other alloyed materials