Observation of Negative Differential Conductance in a Reverse-Biased Ni/Ge Schottky Diode

In this letter, we report the experimental observation of negative differential conductance (NDC) in a Ni/Ge Schottky diode. With the aid of theoretical models and numerical simulation, we show that, at reverse bias, electrons tunnel into the high electric field of the depletion region. This scatters the electrons into the upper valley of the Ge conduction band, which has a lower mobility. The observed NDC is hence attributed to the transferred-electron effect. This shows that Schottky contacts can be used to create hot electrons for transferred-electron devices.