Thin-Film Heterojunction Field-Effect Transistors With Crystalline Si Channels and Low-Temperature PECVD Contacts

Heterojunction field-effect transistor devices with thin-film crystalline silicon channels and gate, source, and drain contacts formed by plasma-enhanced chemical vapor deposition (PECVD) at temperatures <200 degrees C have been demonstrated. The gate and source/drain contacts are comprised of hydrogenated amorphous silicon and crystalline silicon, respectively; both grown in the same PECVD reactor. An ON/OFF ratio of >10(6), pinch-off voltage of approximately -0.6 V, turn-on slope of similar to 70 mV/decade, and off-current of similar to 25 fA/mu m have been achieved at process temperatures <200 degrees C.