Drastically improved performance in poly-Si TFTs with channel dimensions comparable to grain size

Poly-Si thin-film transistors (TFTs) with channel dimensions (width, W, and length, L) comparable to the grain size of the film were fabricated and characterized. The grain size of the film was enhanced by Si ion implantation followed by a low-temperature anneal. A remarkable improvement was observed in the device performance as the channel dimensions decreased to W = L = 2 μm. The TFTs with submicron channel dimensions were characterized by an extremely abrupt switching in their transfer characteristic. The improvement was attributed to the floating-body effect as well as the minimization of the grain boundary effect. It is believed that the results obtained will have impact in the development of large-area devices such as active-matrix liquid-crystal displays and image sensors with on-glass circuits.