The invention provides a semiconductor device, comprising a substrate, a gate electrode on the substrate, a gate insulating layer on the gate electrode, an amorphous oxide semiconductor on the gate insulating layer and source and drain metal electrodes on the amorphous oxide semiconductor at two sides of the gate electrode, and the basic structure is a TFT ultraviolet detector. The semiconductor is an amorphous oxide semiconductor with a broad bang [band] gap (>3.0eV), and the material component can be a ZnO semiconductor doped with In, specifically comprising InGaZnO, InZanO, HfInZnO, TaInZnO, ZrInZnO, YInZnO, AlInZnO and SnInZnO; wherein the atomic counting ratio of [In] to a sum of [In] and [a third metal] is from 35% to 80%, and the atomic counting ratio of [Zn] to a sum of [In] and [Zn] is from 40% to 85%. Preferable atomic counting ratio of elements is that the ratio of [In], [the third metal], [Zn], and [O] is 1:1:1:1 or 1:1:1:2 or 2:2:2:1, or 1:1:1:4, etc. In addition, the semiconductor can be of a material such as In2O3, ZTO, ITO, ZnO, SnOx in an amorphous state. The TFT ultraviolet detector based on the invention has advantages of high efficiency, low cost and evenness for a large area due to the adoption of the amorphous oxide semiconductor.