Gate-All-Around Single-Crystal-Like Poly-Si Nanowire TFTs With a Steep-Subthreshold Slope

Abstract

We investigate the characteristics of single-crystallike (SCL) poly-Si nanowire (SCL poly-Si NW) thin-film-transistors with gate-all-around (GAA) structures. The GAA SCL poly-Si NWs are prepared by a modified sidewall spacer process utilizing an amorphous silicon (alpha-Si) mesa structure. The combination of the high surface-to-volume ratio of the NW and a nominal gate length of 0.25 mu m lead to clear improvement in electrical performance, including a steep subthreshold swing (90 +/- 15 mV/dec), a virtual absence of drain-induced barrier lowering (21 +/- 13 mV/V), and a very high ON/OFF current ratio similar to 7 x 10(7) (V-D = 1 V, V-G = 3 V).