Identification of Point Defects in Multielement Compounds and Alloys with Positron Annihilation Spectroscopy: Challenges and Opportunities

Three topical materials systems are discussed from the point of view of point defect characterization with positron annihilation spectroscopy. The family of III-nitride semiconductors and device structures made thereof poses interesting challenges for data interpretation due to preferential localization and annihilation with various elements. Semiconducting oxides with relatively complex crystal lattice structures further highlight the need for combining systematically designed experiments with state-of-the-art theoretical calculations. High-entropy alloys generate another challenge due to the large number of randomly distributed elements, combining chemical disorder with structural order.