Amorphous silicon bulk barrier phototransistor with Schottky barrier emitter

An amorphous silicon indium tin oxide/n+-i-δ( p+)i/Al Schottky barrier phototransistor was fabricated on a glass substrate, where δ( p+) is the thin (200 Å) p+ base. The operation of the transistor is similar to that of an n+-i-δ( p+)i-n+ amorphous silicon bulk barrier phototransistor. Photogenerated holes are accumulated at the thin base region (barrier valley) and induce a large number of electrons injected from the Schottky barrier due to the hole induced barrier lowering. Varying the emitter and collector i-layer thickness produced different current gains in which a maximum value of 5.6 is obtained for the 300-Å emitter i-layer/p+/3000-Å collector i-layer structure under an input red light intensity of 7.5 mW/cm2.