Optical determination of the band gap and band tail of epitaxial Ag2ZnSnSe4 at low temperature

Abstract

We report on the precise determination of both the band gap E g and the characteristic energy U of the band tail of localized defect states, for monocrystalline Ag 2 ZnSnSe 4. Both photoluminescence excitation and timeresolved photoluminescence studies lead to E g = 1223 ± 3 meV, and U = 20 ± 3 meV, at 6 K. The interest of the methodology developed here is to account quantitatively for the time-resolved photoluminescence and photoluminescence excitation spectra by only considering standard textbook density of states, and state filling effects. Such an approach is different from the one most often used to evaluate the energy extent of the localized states, namely by measuring the energy shift between the photoluminescence emission and the excitation one-the so-called Stokes shift. The advantage of the present method is that no arbitrary choice of the low power excitation has to be done to select the photoluminescence emission spectrum and its peak energy.

Wet Chemical Synthesis and Optical Properties of Co2+-Doped Magnesium Stannate Ceramics

“…This was previously observed for several spinels such as MgGa 2 O 4 :Co 2+ 43,44 , ZnGa 2 O 4 :Co 2+ 44,45 , and MgGa 2 O 4 :Cr 3+ 46 . Some authors showed results of bandgap calculation using PLE instead of UV-VIS absorption spectroscopy with results close to those obtained with absorption spectroscopy [47][48][49][50] . In this way, considering the possibility of the similarity between PLE and absorption spectra of the Mg 2 SnO 4 :Co 2+ , as seen in references [43][44][45] , the bandgap value for the Mg 2 SnO 4 :Co 2+ of the most emitting sample (0.08 at mol% of Co 2+ ) was estimated from PLE spectra.…”

LSPR of Nanoparticles Inside Strong Absorbent Medium

“…In 1966, Tauc and his team further simplified the law into a power equation, which has become known today as Tauc’s law. An optical reflection spectra can be used to estimate the E g of semiconductors using Tauc’s method, which is applicable to both amorphous and crystalline nanomaterials. − …”