The temperature dependence of the fundamental band-gap E0 of Cd1−xZnxTe alloys with zinc concentrations in the 0 to 0.3 range has been determined by modulated photoreflectance (PR). E0 is found to vary from 1.511 eV for x=0.00 to 1.667±0.008 eV for x=0.3, at room temperature and from 1.602 eV at x=0.00 to 1.762±0.004 eV for x=0.3 at 10 K. The measured broadening parameters Γ have values between 25 and 45 meV at room temperature and decrease monotonically to values around 5 meV or smaller at 10 K. The temperature dependence of the observed band gap energies is well described by the well known Varshni formula E(T)=E(0)−AT2/(T+Θ) for all samples studied. The PR temperature broadening is well understood assuming that it results from the scattering of the excitonic electron-hole pair responsible of the band-to-band transition PR signal off LO phonons.
Refractive indices n and absorption coefficients α of epitaxial metastable zincblende structure β-GaN(001) were determined over the subband-gap energy range between 0.8–3.1 eV from an analysis of optical transmission spectra. n was found to vary from 2.25 to 0.8 eV (1.55 μm) to 2.50 at 3.1 eV (0.4 μm) with an energy E (eV) dependence that is well described by a Sellmeir-type dispersion relationship, n2(E)=1+148/(38.3−E2). The refractive indices of β-GaN are 3%–4% smaller than previously reported values for hexagonal α-GaN.
Hadamard, cosine, and noiselet basis are implemented into a digital holographic microscope based on single-pixel imaging with the capability to retrieve images of complex objects. The object is illuminated with coherent light modulated with different patterns deployed in a digital micromirror device, and the resulting fields are captured by single-pixel detection. For amplitude images, the experimental results of the three basis are evaluated with the peak signal-to-noise ratio criteria. It is shown that the cosine basis recovers amplitude distributions with the best quality. Regarding phase images, the recovered ones compare well with those obtained with a CMOS camera.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.