Present status and prospects of rare-earth-doped semiconductors

Abstract

The luminescent and magnetic properties of rare-earth (RE) elements doped in insulators and metals have been thoroughly investigated, and they have been successfully applied to practically used fluorescent substances and magnets. In these applications, however, either the luminescent or the magnetic property of the RE elements has been independently used. Furthermore, research on RE-doped materials has been based on experience obtained through trial and error, not on material design by the precise control of RE doping and understanding of the energy-transfer mechanism. In RE-doped semiconductors with atomic-level control, we have studied not only the exploitation of luminescent and magnetic properties but also the exploitation of new functionalities provided by their fusion. In this article, ultrafast energy transfer from a GaAs host to Er ions and the cooperative behavior between Er ions found in Er,O-codoped GaAs are described. Room-temperature red electroluminescence is also demonstrated in Eu-doped GaN light-emitting diodes under current injection.