According to another embodiment, a method of forming a transistor is provided. The method includes the following operations: providing a substrate; providing a source over the substrate; providing a channel connected to the source; providing a drain connected to the channel; providing a gate insulator adjacent to the channel; providing a gate adjacent to the gate insulator; providing a first interlayer dielectric between the source and the gate; and providing a second interlayer dielectric between the drain and the gate, wherein at least one of the formation of the source, the drain, and the channel includes about 20-95 atomic percent of Sn.