A detailed optical study of the metastable III/V semiconductor alloy InP1−xSbx is presented. InP1−xSbx layers are grown throughout the entire compositional range by atmospheric pressure organometallic vapor phase epitaxy on InP, InAs, and InSb substrates. Composition and strain are measured by combined electron microprobe analysis and x-ray diffractometry. The dependence of band gap on composition is experimentally established for the first time from absorption spectra measured at 10 and 300 K. The resultant value of the band-gap bowing parameter is 1.52±0.08 eV, independent of temperature. The absorption spectra show the InP1−xSbx layers to have long band tails, which extend further into the gap as the Sb concentration is increased. The band tails are induced by compositional clustering. Photoluminescence (PL) spectra are measured between 10 and 300 K. The PL peaks are assigned to recombination between carriers occupying band-tail states or to recombination via deep centers in the gap.

The photoluminescence (PL) from thin GaInAs/InP single quantum wells (SQWs) grown by atmospheric pressure organometallic vapor phase epitaxy is investigated. The 10-K PL intensity from the SQWs is as much as 25 times stronger than that from approximately 1.5-μm-thick epitaxial GaInAs layers. The underlying PL processes, namely photogeneration of carriers, carrier collection by the well, and recombination in the well, are studied. The photogeneration of carriers in the well is calculated to be negligible compared to that occurring in the InP barriers. In contrast, the quantum-well PL is approximately a factor of 4500 stronger than the barrier PL for all samples at temperatures ranging from 10–300 K. This necessitates rapid and efficient transfer of photogenerated carriers from the barriers into the well. The transfer is investigated by applying a rate equation model relating the barrier and quantum well PL intensities to the lifetimes governing the recombination dynamics in the barriers and in the well. The transfer is calculated to occur within a few picoseconds at 10 K with nearly 100% transfer efficiency. The temperature dependence of the barrier PL spectra shows that the carrier-collection efficiency of the well remains high up to room temperature. The integrated quantum-well PL intensity decreases by approximately two orders of magnitude as the temperature is raised from 10 to 300 K, which is attributed to a decrease of the radiative quantum efficiency of the well. Results of a PL-excitation study suggest that the PL is due to interface- or cluster-localized exciton recombination at 10 K at low excitation intensities. At high temperatures and excitation intensities, the PL spectra show evidence for delocalization and/or dissociation of the excitons.

GaInAs/InP quantum wells were grown by using atmospheric pressure organometallic vapor-phase epitaxy with and without interruptions at the interfaces. The growth schedule has a major effect on the optical properties of the quantum wells. For approximately 10-Å-thick wells, the ground-state energy as determined by 10-K photoluminescence decreases in the following order: continuous growth, an interruption at the second interface, and interruptions at both interfaces. It is demonstrated that As is effective in substituting for P atoms on the InP surface during AsH3 purge. Varying the AsH3 flow rate during growth of the GaInAs well layer significantly influences the emission energies for samples grown continuously or with an interruption at the second interface. However, the emission energies of quantum wells grown with interruptions at both interfaces are found to be independent of the AsH3 flow rate, indicating insignificant substitution of As for P in the InP barriers. An interfacial layer of InAsxP1−x may play a dominant role in determining the emission energies for quantum wells thinner than 50 Å.

Articles you may be interested inStructural characterization of very thin GaInAs/InP quantum wells grown by atmospheric pressure organometallic vaporphase epitaxy High quality narrow GaInAs/InP quantum wells grown by atmospheric organometallic vapor phase epitaxy Appl. Phys. Lett. 49, 1384 (1986); 10.1063/1.97625GaInAs/InP quantum wells grown by organometallic vapor phase epitaxy

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