The Comparisons between GaP Window Layers of Double-Heterojunction Light-Emitting Diodes using Various Dopants and Source Melts Regrown by Indium-Addition Liquid Phase Epitaxy

Abstract

The p-GaP window layer of surface-emitting InGaAlP/InGaP double heterojunction (DH) light-emitting diodes (LEDs) regrown using Ga and Sb source melts by In-addition liquid phase epitaxy (LPE) system is studied in this work. The Sb metal is introduced into the source melt in order to eliminate the phenomenon of melt back at dice edges, which occurs when using a Ga source melt during the LPE regrowth process. The GaP window layers regrown from pure Sb or Sb–In melt are free from antimony and are characterized by energy dispersive analysis of X-ray (EDAX). The solubility of GaP at different source melts is also investigated by the weight loss method. The GaP window layer with Zn doping is adopted in view of the ohmic contact of the device whose top layer must have a high concentration, and the p-type impurity of Zn with a high distribution coefficient is more suitable than Mg for doping atoms. The incorporation of In enormously enhances the growth rate during the regrowth process. By using the GaP window layer grown by In-addition LPE using a Sb source melt, the LEDs have a high breakdown voltage and maintain the same order cut-in voltages as the original LED (without a GaP window layer). The LEDs with a GaP window layer have better light output power performances than those without a GaP window layer.