Highly stable GaN-based betavoltaic structures grown on different dislocation density substrates

Abstract Betavoltaics is a potentially attractive solution for ultra-long lifetime power sources. However, reliability of such devices depends on the radiation hardness of the semiconductor system. III-N semiconductors (nitrides) are known to be unusually strongly bonded materials, able to withstand relatively high doses of radiation. Gallium nitride structures can be grown either on sapphire templates with high dislocation density or on GaN substrates which ensures much better quality and perhaps performance of the final device. Therefore, the interest of this paper is to explore. p-i-n GaN junctions grown on various types of substrates and to find the best system for future betavoltaics batteries. Within the present work we demonstrate the design, modelling, and the tests of betavoltaic structures based on GaN p-n junction. The structures grown on high quality GaN substrates showed better efficiency at small excitation than counterparts grown on sapphire with power conversion efficiencies up to 3%. We do not observe any degradation in the studied structures after reliability testing, that consisted of electron irradiation in a scanning electron microscope or directly using Ni-63 radioisotope and also in an electron accelerator. All experiments indicate suitability of GaN for the construction of betavoltaic cells.