The origins of the leakage currents of p-n junction and Schottky diodes in all kinds of materials: A novel explanation based on impurity-photovoltaic-effect due to the self-absorption of the room-temperature infrared emission from materials

Abstract

A p-n junction is the basic building block for various semiconductor devices. A Schottky diode has characteristics that are essentially similar to those of the p-n junction diode. As is known, the leakage currents of p-n and Schottky junctions affect the overall performance of the devices and reduce the reliability of the devices. In order to achieve optimum device design, it is essential to fully understand the physical principle of the leakage currents. In traditional theory, defects provide a path for leakage current to travel. In this study, a novel theoretical model based on impurity-photovoltaic-effect is proposed to explain the leakage currents. It is well known that any object at a room-temperature emits infrared (IR) photons due to blackbody radiation. As is also well known, there is no absolutely pure material, and any material contains unavoidable defects associated with impurities. The self-absorption of the IR emission could be achieved through the sub-band-gap excitations due to defect-related intermediate levels in forbidden energy band-gap, creating carriers (electrons and holes). Some of the carriers diffuse into the built-in electric field of the junction. The built-in field then sweeps out electrons and holes in opposite directions, forming IR-generated photocurrent. Therefore, the leakage current is regarded as photocurrent. In addition to p-n junctions, some junctions exist in many semiconductor devices such as p-i-n diode and charge-coupled device (CCD), and these junctions also have built-in field due to contact potential difference. In fact, every semiconductor device contains at least one junction. The novel model is expected to explain the leakage for all kinds of junctions with semiconductor built-in fields.