Germanium Thin Film Formation by Low‐Pressure Chemical Vapor Deposition

Thin films of polycrystalline germanium were formed by the pyrolysis of germane gas in a low-pressure reactor. Process parameters investigated were deposition temperature in the range 250 to 350°C and pressure in the range 300 to 600 mTorr. The properties of the film have been characterized using transmission electron microscopy and x-ray diffrac-tion for structural analysis, atomic force microscopy for surface morphology analysis, secondary ion mass spectroscopy for compositional analysis, and Hall effect measurement for electrical parameter extraction, etc. High Hall effect mobil-ity on the order of 300 cm2/V s was obtained, even at a relatively low deposition temperature of 300°. This makes the ger-manium thin films potentially very promising for low-temperature device processing. Infroduction Polycrystalline thin film transistors (TFTs) have been used in a number of important applications. These include three-dimensional stacked transistors for static random-access memories, pixel and drive transistors for liquid crystal display panels, and integrated sensors, etc. In many such applications, low processing temperature is re-