Investigation of Er-doped 1.55μm InGaAsP single-heterostructure light-emitting diodes

Abstract

Er-doped InGaAsP layers with wavelengths of 1.3 and 1.55 μm were grown on InP substrates by liquid-phase epitaxy. Effects of Er doping on structural, optical and electrical properties have been examined. The dominant process occurring during the growth of InGaAsP layers in the presence of elemental Er is a very efficient gettering of residual donors observed by the decrease in the electron concentration and the narrowing of the full width at half maximum of photoluminescence. The 16 K Er-related luminescence lines are only observed for the 1.3 μm wavelength InGaAsP layer and locate around 1.50-1.54 μm, but their intensity is three orders in magnitude weaker than that of the 16 K near-band-gap peak. Diodes fabricated from the Zn-doped In 0.75Ga 0.25As 0.56P 0.44/Er-doped In 0.58Ga 0.42As 0.89P 0.11 single heterostructure exhibit a forward-bias turn-on voltage of 0.5 V and an ideality factor of 2.04. By electroluminescence measurements, the emission peak wavelength and the external quantum efficiency of these uncoated light-emitting diodes are around 1.53 μm and 0.25%, respectively. The lack of Er-related lumicescence in the 1.55 μm wavelength layer or single-heterostructure wafer is consistent with the conclusion arrived at by Van der Ziel, Oberg and Logan. The main obstacle to obtain the good performance of this diode is attributed to the low electron concentrations and the deep levels introduced in the Er-doped InGaAsP layers.