Neutron and Proton Radiation Damage and Isothermal Annealing of Irradiated SiC Schottky Power Diodes

Abstract

NASA is exploring the potential use of nuclear reactors as power sources for future missions. These missions will require semiconductor switches to be placed in close vicinity to the reactor, in the midst of a high neutron and gamma radiation field. Cree SiC Schottky diodes, part number CSD10120A, rated at 10 A and 1200 V, were chosen as the test articles for this radiation‐hardness study, since SiC is a wide bandgap semiconductor that has exhibited tolerance for such high radiation environments. As an extension of previous work regarding the degradation of SiC Schottky diodes in the presence of a neutron and gamma radiation field, isothermal annealing experiments were performed on these diodes after they were irradiated in The Ohio State University Research Reactor (OSURR). The experimental results demonstrate that even at an anneal temperature of only 175 C, a noticeable improvement in the electrical performance of the diodes, in the form of decreased series resistance, may be readily observed from I‐V curve measurements. Also, since electrical components used for space applications will also be exposed to charged particle radiation from space, such as high energy protons in the Van Allen Radiation Belts surrounding earth, it is important that, in studying the effects of radiation‐induced displacement damage, the effects of both neutron and charged particle radiation are considered. Therefore, the data obtained from this study were compared with the data obtained from previous 203 MeV proton irradiations, for which the same diode model was tested. To develop neutron‐proton equivalencies which are relevant to the radiation electronics hardening community and the materials science community, comparisons of the degradation of the diodes for proton and neutron irradiation are made in two ways 1) on the basis of displacement damage dose, Dd for protons and neutrons; and 2) on the basis of initially induced vacancies per atom (at a temperature of 0 K) (IIVPA0) for protons and Displacements per Atom (DPA) for neutrons. The equivalencies are especially good when the comparisons are made on the basis of IIVPA0, and DPA.