JPS5635480A - Light emitting diode - Google Patents

Abstract

PURPOSE:To improve the light emitting efficiency of the light emitting diode by bonding a crystal having the same conductivity type as the front and back surfaces of a GaAsP crystal having a P-N junction and larger energy gap than the crystalline surface thereof to the front and back of the GaAsP crystal. CONSTITUTION:When the P-N junction B of a GaAsP layer is forwardly biased, electrons 8 injected from an n type layer to a p type layer move within a diffused distance, and are recombined with holes 10. The junction depth is sufficiently increased in length as compared with the diffused distance, the light is absorbed in the crystal before the light is picked up from the surface, and light emitting efficiency is thus enhanced. Since the thickness L of the p type GaAsP layer is formed equally to the electron diffused distance and is bonded to the p type GaP of a band gap Eg1>Eg2, uncombined electrons 9 in the p type GaAsP reach the p type GaAsP layer. However, the electron 9 is moved to the low energy level transmission band, is recombined with the holes 10, and emits photons 12, and becomes in the energy equal to Eg2. Since it incorporates the front and back layers of Eg1>Eg2, no absorption on the front and back layer surfaces occur, and internal light can be externally picked up.