A silicon-on-insulator (SOI) power device with introduced fixed charges is provided. The SOI power device is a shorted-anodelateral insulated gate bipolar transistor (SA-LIGBT) or separated shorted-anodelateral insulated gate bipolar transistor (SSA-LIGBT) structure, and includes a semiconductor substrate, a dielectric buried layer, and a semiconductor active layer stacked in sequence, where a first charge layer is provided between the dielectric buried layer and the semiconductor active layer, and/or a second charge layer is provided between a field oxide layer and the semiconductor active layer; and the charge layer carries continuously and uniformly distributed positive charges. The snapback present in the output characteristics of the traditional SA-LIGBT or SSA-LIGBT is addressed. By inserting the fixed charges between the dielectric buried layer and the semiconductor active layer, the SOI power device reduces the voltage of the snapback effect and significantly suppresses the occurrence of the snapback phenomenon.

According to one embodiment, wafer includes a substrate including silicon carbide. The substrate includes a first face and a second face. The substrate includes a first region between the second face and the first face in a first direction from the second face to the first face, a second region between the second face and the first region in the first direction, and a third region between the first region and the first face in the first direction. The first region includes a first element including at least one selected from the group consisting of fluorine and oxygen. A first concentration of the first element in the first region is higher than a second concentration of the first element in the second region, and higher than a third concentration of the first element in the third region.

According to one embodiment, wafer includes a substrate including silicon carbide. The substrate includes a first face and a second face. The substrate includes a first region between the second face and the first face in a first direction from the second face to the first face, a second region between the second face and the first region in the first direction, and a third region between the first region and the first face in the first direction. The substrate includes nitrogen. The first region includes a first element including at least one selected from the group consisting of phosphorus and arsenic. A first concentration of the first element in the first region is higher than a second concentration of the first element in the second region, and higher than a third concentration of the first element in the third region.