Schottky barrier junctions of hydrogenated amorphous silicon-germanium alloys

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Abstract
The current‐transport mechanisms of amorphous Schottky barrier junctions are investigated using both undoped and phosphorus‐doped hydrogenated amorphous silicon‐germanium alloys (a‐Si1−xGex: H) fabricated by rf glow discharges in diode‐ and triode‐reactor systems with and without the dilution of hydrogens. From the experimental results, the forward‐current mechanisms for amorphous Schottky barrier junctions are generally discussed and classified into three categories: (1) field emission, (2) diffusion‐field emission, and (3) diffusion. The diffusion‐field‐emission model (multistep tunneling through a part of the Schottky barrier) used for the first time in this work can interpret the current‐voltage characteristics and their temperature dependence on amorphous Schottky barrier junctions to a high degree. Moreover, the flow chart proposed here classifies the material quality of amorphous semiconductors according to their junction properties. We concluded that one of the better methods to fabricate high‐quality a‐Si1−xGex: H for Schottky barrier junctions is the triode‐reactor technique using hydrogen‐diluted starting‐gas materials.