Sputtering method for making thin film field effect transistor utilizing

Abstract

Thin film field effect transistors utilize MP.sub.x as the active switched semiconductor where M is at least one alkali metal, P is at least one pnictide, and x ranges from 15 to infinity. Phosphorus is preferred as the dominant pnictide and potassium is preferred as the dominant alkali metal. The local order of the semiconductors may vary from an all parallel pentagonal tube-like structure to a layer-like puckered sheet structure. The all parallel pentagonal tube structure is preferred. Metal insulated semiconductor (MISFETS) and metal semiconductor (MESFETS) field effect transistors are disclosed. The semiconductor is preferably doped with up to approximately 1/2% nickel, iron, or chromium, to reduce the density of defect levels in the bandgap without increasing the conductivity. The semiconductors may be doped with 1/2-1% of the same metals to increase conductivity so as to provide normally ON devices. The regions of a semiconductor under the source and drain may be heavily doped with 2-3% of the same metals to provide good contact to the source and drain. Nickel is the preferred metal.