Electrical properties of polycrystalline germanium-metal films

Abstract

The electron transport properties of crystalline and crystallized Ge-metal (Al, Ga, Ag, Au, Cu and Fe) films were studied as functions of the metal concentration (up to 10 at.%) and temperature (150-500 K). The addition of aluminium and gallium decreases the electrical resistivity and thermoelectric power (TEP). The carrier concentration increases rapidly and there is a gradual decrease in the Hall mobility. Silver affects these transport properties only slightly in crystalline films but large effects are observed in crystallized Ge-Ag films. There is a gradual decrease in the electrical resistivity and TEP of crystalline and crystallized Ge-Au films. The carrier concentration increases slowly and the Hall mobility shows a maximum. The carrier concentration in crystalline Ge-Cu and Ge-Fe films decreases slowly but shows an increase in the corresponding crystallized films. The Hall mobility in crystalline films decreases but shows a maximum in the crystallized films. In crystalline Ge-Cu films the TEP decreases initially (up to approximately 2 at.% Cu) and then increases. The electron transport properties in these films are explained in terms of the formation of solid solution/segregated ordered phases.