Direct-bandgap electroluminescence from a horizontal Ge p-i-n ridge waveguide on Si(001) substrate

Horizontal injection Ge p-i-n ridge waveguide light emitting diodes (LEDs) were fabricated on n(-)-Si(001) substrates by ultrahigh vacuum chemical vapor deposition. The direct-bandgap electroluminescence (EL) of Ge waveguide LEDs under a continuous/pulse electrical pump was studied. The heating effect from a continuous electrical pump was found to significantly enhance the emission of devices. The top surface EL intensity of the Ge waveguide LEDs significantly depended on the position. Most direct-bandgap radiative recombination of Ge p-i-n waveguide LEDs occurred near the N+ region of the junction. This interesting phenomenon could be explained by the carrier distribution in the junction and the pseudo-direct bandgap of Ge. (c) 2014 AIP Publishing LLC.