This critical review surveys beta-FeSi2 research over the years with focus on reviewing recent development in beta-FeSi2-based light emitting diodes (LEDs). Based on theoretical analyses and comparison to experimental results reported in the literature, weak carrier confinement in the beta-FeSi2 active layer has been identified as the likely cause for poor room-temperature electroluminescence (EL) performance of p-Si/p-beta-FeSi2/n(+)-Si double hetero-junction LEDs. Solutions to overcome this limit have been proposed together with new research directions. (C) 2013 Elsevier B.V. All rights reserved.