Assessment of the structural and electronic properties of GaxIn1−xP semiconductors for betavoltaic energy conversion systems

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Vol. 528; pp. 1 - 7
• Main Authors: Kaloni, T.P., Ellis, B., Torres, E.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2022
• Subjects: Bandgap; Betavoltaics; DFT; GaInP; Radiation damage; Tritium; Tritium; DFT; GaInP; Radiation damage; Bandgap; Betavoltaics
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/j.nimb.2022.07.004

Indium gallium phosphide (GaxIn1−xP) semiconductors are attractive for betavoltaic batteries because of their excellent structural, thermophysical, and electronic properties. In the present work, we investigate the structural strength and electronic properties of zinc-blende GaxIn1−xP systems, for 0≤x≤1, using first-principles calculations. The most stable structures for different compositions are determined by a systematic evaluation of the atomic configurations. The dynamical stability of the structures is verified by examination of the phonon spectra. To assess the tolerance to radiation damage, we evaluated the minimum threshold displacement energy (Ed) for each atom type in the system. The Ed is estimated from simulations of recoil atom events using ab-initio molecular dynamics. We find a substantial effect of the composition on the electronic properties. In particular, the bandgap is relatively low for 0<x<0.5. The Ed was found to mainly depend on the crystallographic direction for In and P, whereas a considerable effect of the composition is observed for Ga. Overall, GaInP is found to be the more resistant to the radiation-induced degradation and the bandgap is also less affected by structural damage. Therefore, our results indicate that Ga0.25In0.75P is overall an excellent candidate for tritium-based betavoltaic batteries. •We have investigated the electronic and radiation damage properties of the GaxIn1-xP systems using atomistic scale simulations. Our results provide information on the semiconductor behavior under irradiation conditions.•In particular, this study has identified the effect of irradiation damage on the bandgap as a function of the compositions. Such damage resulting in the loss in efficiency of the betavoltaic energy conversion in the long term, which poses a considerable challenge towards the practical application of betavoltaic batteries.•Therefore, the assessment of radiation damage in this study provides significant information to guide in-lab demonstrations.