Schottky Diode with Asymmetric Metal Contacts on WS₂

Diode characteristics of transition metal dichalcogenides are studied extensively owing to their electrical and optical properties. In particular, the Schottky barrier diode (SBD) structure has advantages, such as its small leakage current and power consumption, over conventional p–n diodes. This study develops an SBD system using n-type tungsten disulfide (WS₂). By depositing a low work function In (Φ_In = 4.1 eV) and high work function Au (Φ_Au = 5.1 eV) on n-type WS₂, the diode characteristics are demonstrated to be close to an ideal diode. The In–Au contacts are measured, and SBD characteristics are confirmed with a 1.02 ideality factor at a zero back-gate voltage at room temperature and a rectification ratio up to 5 × 10², even at a low temperature (77 K), indicating almost ideal diode properties. In addition, the In electrodes exhibited improved electrical properties, with a high on/off ratio of 10⁷, mobility that is 100 times higher, and Schottky barrier height that is 20 times lower than that of Au electrodes.