The present invention discloses a semiconductor device, a thin film transistor (TFT), and a process for forming a TFT. The semiconductor device according to the present invention comprises a top-gate type thin film transistor (TFT), said top-gate type TFT being formed on a substrate, said top-gate type TFT comprising: an insulating layer deposited on said substrate; a source electrode and a drain electrode formed from a metal-dopant compound, said metal-dopant compound being deposited on said insulating layer; a polycrystalline Si (poly-Si) layer deposited on said insulating layer and said source electrode and said drain electrode; an ohmic contact layer being formed between said metal-dpoant compound and said poly-Si layer through migration of said dopant from said metal-dopant compound; a gate insulating layer deposited on said poly-Si layer; and a gate electrode formed on said gate insulating layer, wherein said poly-Si layer is crystallized by metal induced lateral crystallization.