  Van der Waals heterostructures formed by stacking of various two-dimensional
materials are promising in electronic applications. However, the performances
of most reported electronic devices based on van der Waals heterostructures are
far away from existing technologies'. Here we report high performance
heterostructure devices based on vertically stacked tungsten diselenide and tin
diselenide. Due to the unique band alignment and the atomic thickness of the
material, both charge carrier transport and energy barrier can be effectively
modulated by the applied electrical field. As a result, the heterostructure
devices show superb characteristics, with a high current on-off ratio of around
3 x 108, an average subthreshold slope of 126 mV per decade over five decades
of current change due to band to band tunneling, an ultra-high rectification
ratio of around 3 x 108 and a current density of more than 104 A per cm2.
Further, a small signal half wave rectifier circuit based on majority carrier
transport dominated diode is successfully demonstrated, showing great potential
in future high speed electronic applications.
