Anomalous Blue Shift of Exciton Luminescence in Diamond

Abstract

Generally speaking, for a semiconductor, the temperature dependence of excitonic emission corresponds to that of its band gap. However, an anomalous behavior is exhibited by the excitonic luminescence of diamond where as the temperature increases (from 10 to 300 K), its indirect exciton luminescence peak displays a spectral-distinguishable blue shift, whereas the indirect band-gap absorption shows a weak red shift. According to experimental high-resolution deep-ultraviolet spectra and theoretical analysis, the weak red shift of its indirect band gap is ascribed to its large Debye temperature (ΘD ≈ 2220 K), which makes the lattice constant change comparatively little in a large temperature range, so the change of its band gap is relatively small; in this case, as the temperature rises, the thermal population of valence-band holes that moves to a high-energy state far away from the Fermi surface contributes to the macroscopic blue shift of its excitonic emission.

Wafer-sized polycrystalline diamond photodetector planar arrays for solar-blind imaging

“…By plotting ( αhν ) 0.5 versus hν and extrapolating the absorption edge to the x -axis, a band gap of 5.46 eV can be obtained. 40 From the PL spectrum in Fig. 2(c) we can see the second-order Raman peak of diamond at 680 nm, nitrogen-vacancy (N-V) color centers at 575 nm, the phonon-sideband emission, and silicon-vacancy (Si-V) color centers at 738 nm, indicating that a certain amount of nitrogen exists in the polycrystalline diamond.…”

Millimeter-Sized Monoisotopic Cubic 10Boron Phosphide

“…Five luminescence peaks of 10 BP single crystals are obtained after the Gaussian fitting, which are at 635.6, 670, 694.4, 809.7, and 889.6 nm, respectively. Combining the reflectance spectrum with calculations, the multipeak photoluminescence of 10 BP single crystals should be attributed to the radiation recombination of bound excitons centered on defects. − …”

Switchable biexcitons in perovskite-like RbCu2Br3 crystals driven by thermally induced phase transition

“…42 It is worth noting that the RbCu 2 Br 3 crystals exhibited an anomalous trend, that is, the luminescence intensity decreases with lower temperature at STE (B) and STE (O) . Negative activation energy (− E a ) processing can be introduced in this descending stage: 43–45 as shown in Fig. S6b and c (ESI†), the dotted line is the fitting result of formula (3), from which the results − E a (STE (B) ) = −1.198 meV and − E a (STE (O) ) = −1.937 meV are achieved.…”

“…42 It is worth noting that the RbCu 2 Br 3 crystals exhibited an anomalous trend, that is, the luminescence intensity decreases with lower temperature at STE (B) and STE (O) . Negative activation energy (ÀE a ) processing can be introduced in this descending stage: [43][44][45] IðTÞ ¼…”