Gene Tsai

Molecular beam epitaxial growth of InAsN:Sb for midinfrared Optoelectronics

We report molecular beam epitaxial growth and characterization of dilute nitride InAsN:Sb. X-ray diffraction, energy dispersive x-ray spectrometry, and electron probe microanalysis revealed that nitrogen incorporation is significantly enhanced by introduction of Sb flux during growth, together with a dramatic improvement of the photoluminescence. These observations were attributed to the surfactant effect of Sb which suppresses the surface diffusion length of nitrogen and improves the homogeneity of the alloy. Sb incorporation is enhanced with the presence of nitrogen which was associated with the surface kinetic of growth. InAsN:Sb∕InAs p-i-n light emitting diodes operating near 4.0μm were also realized.

Midinfrared Photoreflectance Study of InAs-rich InAsSb and GaInAsPSb Indicating Negligible Bowing for the Spin Orbit Splitting Energy

The authors report on midinfrared photoreflectance measurements of the band gap (E0) and spin-orbit splitting energies (Δ0) in InAs-rich InAsSb and GaInAsPSb samples for varying antimony contents ⩽22.5%. The E0 behavior as a function of Sb content is consistent with the literature value bowing parameter of ∼670meV. However, Δ0 does not exhibit the positive bowing of +1170meV quoted in the literature: rather, a best fit to their data tentatively suggests a negative bowing of −225meV. This result is likely to have strong impact due to the importance of the Δ0 parameter in governing InAsSb-based device performance.

Mid-infrared electroluminescence at room temperature from InAsSb multi-quantum-well light-emitting diodes

Room-temperature electroluminescence is reported from InAsSb multiple-quantum-well light-emitting diodes. The diodes exhibited emission in the mid-infrared peaking near 4μm. The spectral dependence on injection current at 4K was investigated and two transitions were identified, centered at 4.05 and 3.50μm, which are associated with the eigenstates of the confined holes inside the quantum well. The use of an Sb predeposition and As flux surface exposure during epitaxial growth was observed to have a major effect on the electroluminescence output.

Photoluminescence and bowing parameters of InAsSb∕InAs multiple quantum wells grown by molecular beam epitaxy

Detailed studies are reported on the photoluminescence of InAsSb∕InAs multiple quantum wells grown by molecular beam epitaxy on InAs substrates with the Sb mole fraction ranging from 0.06 to 0.13. From 4K photoluminescence the band alignment was determined to be staggered type II. By comparing the emission peak energies with a transition energy calculation it was found that both the conduction and valence bands of InAsSb alloy exhibit some bowing. The bowing parameters were determined to be in the ratio of 4:6. For a sample with Sb composition ∼0.12 in the quantum well the photoluminescence emission band covers the CO2 absorption peak making it suitable for use in sources for CO2 detection.

Photoluminescence of InAs0.04P0.67Sb0.29

We report the results of a detailed photoluminescence (PL) study on quaternary InAs0.04P0.67Sb0.29 grown by gas-source molecular-beam epitaxy. The main PL peak at 10 K shows a transition energy that is lower than the calculated energy gap by 0.223 eV, which is attributed to the tail states recombination. Another PL band, which emerges as the temperature increases, is assigned to the self-activated luminescence from defect centers. Its features, namely, nearly temperature-independent peak energy, Gaussian-like lineshape, and square-root-of- temperature-dependent linewidth, can be illustrated by the configuration coordinate model. The vibration energy, calculated from the linewidth at low temperature, is 0.022 eV for the excited state of the defect centers. The self-activated luminescence shows a thermal quenching behavior that is usually exhibited by amorphous semiconductors, indicating that the defects are related to the compositional disorder. The defects responsible for the luminescence are most likely ...

Band alignment of InAs1−xSbx (0.05<x<0.13)/InAs0.67P0.23Sb0.10 heterostructures

We determined the unstrained conduction-band and valence-band edge energies of InAs1−xSbx (0.05<x<0.13) by fitting the photoluminescence peak energy of InAsSb/InAs0.67P0.23Sb0.10 quantum wells (QWs) that was measured in the temperature range 10–300 K. The results reveal that the QWs exhibit type-I band alignment. Furthermore, the valence band accounts for 65% of the energy-gap bowing of InAsSb. We propose a valence-band anticrossing (VBAC) model to explain the bowing of the valence band in InAsSb. Moreover, the spin-orbit splitting energy of InAsSb calculated by our VBAC model fits well with the experimental results reported in previous studies.

Growth of InAsSb/InAs MQW and InPSb by gas source molecular beam epitaxy

We report the growth of InAsSb/InAs MQWs and InPSb by MBE. The incorporation behaviors of Sb as well as the optical properties are discussed. InPSb with only 65 arcsec DXRD linewidths is obtained.