This paper reports a temperature-dependent (10–280 K) photoluminescence (PL) study of below-bandgap electron-hole recombinations and anomalous negative thermal quenching of PL intensity in InP_1–xBi_x (x = 0.019 and 0.023). Four PL features are well resolved by curve-fitting of the PL spectra, of which the energies exhibit different temperature dependence. The integral intensities of the two high-energy features diminish monotonically as temperature rises up, while those of the two low-energy features decrease below but increase anomalously above 180 K. A phenomenological model is established that the residual electrons in the final state of the PL transition transfer into nonradiative state via thermal hopping, and the thermal hopping produces in parallel holes in the final state and hence enhances the radiative recombination significantly. A reasonable interpretation of the PL processes in InPBi is achieved, and the activation energies of the PL quenching and thermal hopping are deduced.

Bi₄Te₃, as one of the phases of the binary Bi–Te system, shares many similarities with Bi₂Te₃, which is known as a topological insulator and thermoelectric material. We report the micro-Raman spectroscopy study of 50 nm Bi₄Te₃ films on Si substrates prepared by molecular beam epitaxy. Raman spectra of Bi₄Te₃ films completely resolve the six predicted Raman-active phonon modes for the first time. Structural features and Raman tensors of Bi₄Te₃ films are introduced. According to the wavenumbers and assignments of the six eigenpeaks in the Raman spectra of Bi₄Te₃ films, it is found that the Raman-active phonon oscillations in Bi₄Te₃ films exhibit the vibrational properties of those in both Bi and Bi₂Te₃ films.

Photoluminescence (PL) properties of In0.2Ga0.8As/GaAs0.96Bi0.04/In0.2Ga0.8As quantum well (QW) grown on GaAs substrates by gas source molecular beam epitaxy were studied by varying excitation power and temperature, respectively. The type-II transition energy shifts from 1.149 eV to 1.192 eV when increasing the excitation power from 10 mW to 150 mW at 4.5 K, which was ascribed to the band-bending effect. On the other hand, the type-II PL quenches quickly along with fast redshift with the increasing temperature due to the relaxation of the band bending caused by the thermal excitation process. An 8 band k·p model was used to analyze the electronic properties and the band-bending effect in the type-II QW. The calculated subband levels and transition energy fit well with the experiment results, and two thermal activation energies of 8.7 meV and 50 meV, respectively, are deduced.

We present electrically injected GaAs/GaAsBi single quantum well laser diodes (LDs) emitting at a record long wavelength of 1141 nm at room temperature grown by molecular beam epitaxy. The LDs have excellent device performances with internal quantum efficiency of 86%, internal loss of 10 cm^-1 and transparency current density of 196 A/cm². The LDs can operate under continuous-wave mode up to 273 K. The characteristic temperature are extracted to be 125 K in the temperature range of 77∼150 K, and reduced to 90 K in the range of 150∼273 K. The temperature coefficient of 0.3 nm/K is extracted in the temperature range of 77∼273 K.