High selective carrier-type modulation of tungsten selenide transistors by iodine vapor
Despite many decades of substantial research of doping technologies, which are critical for 2D materials used in optical and electrical devices, efforts on selective doping 2D materials are still scarce. Here, a novel band matching doping strategy is introduced in high selective doping WSe2. The key to its realization is the use of dopants whose molecular orbitals closely match the band structure of the 2D materials to be doped. By gradually adjusting the exposure time in iodine vapor, the carrier polarity of WSe2 FET from n-type to p-type can be reversely controlled, whereas the carrier type of ReS2, MoS2, MoSe2, MoTe2, and WS2 remain unchanged. The iodine vapor treatment is also utilized in the manufacturing process flow of high-performance p-n homojunction with a near-unity ideality factor of 1.002 along with a current rectification of ~104 and complementary inverter on a single WSe2 nanosheet. Moreover, selective doping allows the WSe2/ReS2 diode to change from n-n to p-n type for the first time and greatly enhances its photodetection capability. This work presents an important progress in selective modulating the electrical properties of a certain material in an integrated multiple 2D materials array.