Mechanism of Mn emission: Energy transfer vs charge transfer dynamics in Mn-doped quantum dots

In the quest for new functional materials, transition metal doping in semiconductors has attracted significant attention, wherein introduction of dopant atoms alters a range of physical properties of the host such as its optical, magnetic, and electronic properties. Hence, the choice of appropriate dopants to meet the current challenges makes semiconductor doping a highly versatile field. In the past, Mn doping in II-VI semiconductors has been extensively studied. The interest in these systems arises from a prominent orange emission from an optically forbidden state. An extended debate in the literature spanning the last three decades has so far shed light on various anomalous properties of Mn emission, specifically in quantum-confined systems leading to more questions. In this perspective, we review the literature with specific emphasis on the mechanism of Mn emission and an understanding of the electron-hole pathway during the excitation and de-excitation process in doped quantum dots. We explore various phenomena of energy and charge transfer mechanisms along with experiments in support of these phenomena which can eventually lead to a better understanding of spin driven optoelectronics. (c) 2020 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).