A Ge light-emitting diode (LED) is demonstrated using a metal-insulator-semiconductor (MIS) tunneling structure with Ge nanocrystals (NCs) embedded within the insulator. A high-k dielectric insulator was used and the Ge NCs were grown by co-sputtering onto p-type Si substrates. Electron-hole radiative recombination within the Ge NCs (grown within HfAIO) allowed for the observation of infrared emission. Visible light was also detected due to defect-related radiative recombination at the Ge/HfAIO interface. The NC size and Ge content were measured using transmission electron microscopy (TEM), energy dispersive Xray (EDX) spectroscopy and Raman spectroscopy. The peak wavelength from the photoluminescence experiments was lower when HfAIO was used as the dielectric than when HfO(2) was used. This is likely due to the larger band gap of HfAIO, when compared to HfO(2). Crown Copyright (c) 2009 Published by Elsevier B.V. All rights reserved.