Photoluminescence properties of erbium-doped III-V semiconductors.

摘要

The photoluminescence properties of erbium doped GaAs and GaP epitaxial layers grown by metal-organic vapor phase epitaxy (MOVPE) were investigated. Rare-earth doped semiconductors are of interest because of their potential use in optoelectronic devices which combine sharp rare-earth luminescence with the convenience of electrical excitation via the semiconductor host. One desirable feature of rare-earth luminescence is that the emission wavelength shows exceptional stability against changes in temperature. Optical devices made from erbium doped materials are of particular interest because the I13/2 4→I4 15/2Er 3+ emission at 1.54 mum matches the minimum loss region of silica fibers used in optical communications.;Relationships between the growth conditions and the optical, electrical, and physical properties of erbium doped GaAs and GaP were examined. A detailed analysis of the I13/2 4→I4 15/2Er 3+ emission indicated that different erbium source molecules or semiconductor hosts led to the incorporation of several different types of Er3+ centers. The interaction with unintentional oxygen impurities proved to be especially important, leading to the creation of Er-O complexes which showed exceptionally strong, sharp luminescence. In GaAs, these emissions were associated with the efficient Er-2O center. Possible incorporation mechanisms for the Er-2O center were given. In GaP, sharp emissions were proposed to originate from a well-defined Er3+ center with local bonding similar to erbium gallium garnets.;The fundamental energy transfer mechanisms between the rare-earth ion and semiconductor host were also investigated. The characteristics of thermally activated quenching processes were examined by modeling the temperature dependence of the Er3+ emission intensity and decay lifetime. These results were used in conjunction with high pressure photoluminescence experiments to identify the two dominant processes responsible for strong quenching of the Er3+ emission at high temperature. Additionally, the interaction between Er3+ centers and free carriers was shown to be important to excitation and quenching of the Er-2O center in GaAs. The Er3+ emission was greatly reduced in n-type samples, whereas the emission remained strong in p-type samples. A model based on the results of a two-beam experiment indicated the presence of a strong Auger quenching mechanism involving free electrons.