We have measured the temperature dependence of the spectral features in the vicinity of direct band-edge excitonic transitions of single crystals from 25 to 300 K using piezoreflectance (PzR). From a detailed lineshape fit of the PzR spectra, the energies and broadening parameters of the A and B excitons have been determined accurately. The origin of these excitonic transitions is discussed. The transition energies and their splittings vary smoothly with the tungsten composition x, indicating that the natures of the direct band edges are similar for the compounds. In addition, the parameters that describe the temperature variation of the energies and broadening function of the excitonic transitions are evaluated and discussed.

We report a detailed structural and optical characterization of Ga0.46In0.54NxP1−x () films grown by gas-source molecular beam epitaxy on GaAs(001) substrates. The polarized high resolution x-ray rocking curves (HXRC) and contactless electroreflectance (CER) and piezoreflectance (PzR) spectra at room temperature show anisotropic character along the [110] and directions. Ordering-induced superlattice-like microstructure observed in high resolution transmission electron microscope (HTEM) images confirms the spontaneous ordering in Ga0.46In0.54NxP1−x layers. In addition, the temperature dependent optical properties are characterized via polarized PzR measurements in the range between 15 and 300 K. The PzR spectra obtained are fitted using the first derivative of a Lorentzian line-shape functional form. The valence band maximum, crystal field/strain splitting and spin–orbit splitting to conduction band transition energies, denoted respectively as Eg, Eg+Δ12 and Eg+Δ13, are accurately determined. The temperature dependences of these near band edge critical point transition energies are analysed using the Varshni expression and an expression containing the Bose–Einstein occupation factor for phonons. The parameters that describe the temperature variation of the transition energies are evaluated and discussed.