Physical mechanisms of ohmic contact and tunnel diode: A novel explanation in terms of impurity-photovoltaic-effect resulting from infrared self-emission at room-temperature

Abstract

A mechanism of quantum-mechanical tunneling is based on electron-wavefunction and is used to explain ohmic contact as well as tunnel and Zener diodes. Tunneling is the important example of wave-particle duality. In this study, an attempt is made to explain these devices in particle description. As is well known, any object at room-temperature emits infrared (IR) photons due to blackbody radiation. The process of heavy doping can cause a lot of defects, e.g. vacancies and interstitials. The self-absorption of the IR emission could be achieved through sub-band-gap excitations due to defect-related levels in forbidden energy gap, creating carriers. In a heavily doped p-n junction diode, some of the IR-generated carriers diffuse into the junction which has a built-in field in a depletion layer. The built-in field then sweeps out the carriers, producing IR photocurrent. The IR photocurrent is regarded as the reverse current of the p-n junction according to the precedent where impurity-photovoltaic-effect is used to explain circuit devices (arXiv:2510.18226). Also, a reverse bias voltage increases depletion layer width, but carrier diffusion length out of the depletion layer remains unchanged, and more IR-generated carriers created in and near the depletion layer can contribute to the IR current. In addition, heavy doping results in not only a great many IR-generated carriers but also avalanche effect at low voltage. As a result, total reverse current dramatically increases with voltage, thus a Schottky diode can be altered to create an ohmic contact and a p-n diode can become a tunnel diode. Considering the wave-particle duality, the combination of quantum-mechanical and photovoltaic mechanisms is suggested to explain these devices. Each mechanism plays a big or small role in the explanation.