Negative thermal quenching in undoped ZnO and Ga-doped ZnO film grown on c-Al2O3 (0001) by plasma-assisted molecular beam epitaxy

Abstract

Negative thermal quenching (NTQ) was observed in bound exciton emission line in undoped ZnO and the donor-to-valence-band emission in heavily Gadoped ZnO thin films grown on c-Al 2 O 3 (1000) through low temperature photoluminescence spectra. In both cases, the enhanced feature of PL peak intensity occurred in the temperature range of 35-45 K corresponding to the energies of either excitation to the vibrational/rotational resonance states or the involvement of B-valence band considering the activation energy of about 5 meV.

Surface State‐Induced Anomalous Negative Thermal Quenching of Multiferroic BiFeO3 Nanowires

“…The 2D contour plots of E2 defect emission measured in the temperature range of 300–438 K (Figure b) clears shows the enhanced PL emission intensity at higher temperatures. Oxygen vacancy related defect emissions and NTQ behavior has been reported in some oxide systems . However, it is generally difficult to identify defect/trap states’ origin.…”

Ratiometric temperature measurement using negative thermal quenching of intrinsic BiFeO3 semiconductor nanoparticles

“…Oxygen vacancy related defect emissions and NTQ behavior has been reported in some oxide systems. [20][21][22][23][24][25][26][27] Moreover, in our previously published work on multifferoic BFO nanowires (NWs) reasonable interpretation of the photoluminescence NTQ process in BFO NWs and detailed representation of the energy levels and E1, E2, E3, and E4 bands is given. 15 Briey, according to the multi-level model developed by Shibata 28 temperature dependent PL intensity can be expressed by activation energy for the process that increases the PL intensity with increasing temperature -NTQ ðE 0 q Þ and activation energy for the non-radiative channels ðE 00 j Þ.…”

“…The intensity of the defect level emission E2 (523 nm) increases signicantly with temperature, while the intensity of near band emission E1 (482 nm) and other defect levels (E3, E4) emissions show an opposite trend (Fig.3(A)). The difference in the temperature dependence of band edge/near band (E1) and defect level/surface state (E2, E3, E4) emissions causes the change of probe's emission color from pale blue to light green, as shown in CIE color diagram in Fig.3(B).Oxygen vacancy related defect emissions and NTQ behavior has been reported in some oxide systems [20][21][22][23][24][25][26][27]. Moreover, in our previously published work on multifferoic BFO nanowires (NWs) reasonable interpretation of the photoluminescence NTQ process in BFO NWs and detailed representation of the energy levels and E1, E2, E3, and E4 bands is given 15.…”

Citric acid tuned negative thermal quenching of all inorganic copper-based perovskites

“…3–6 This same phenomenon has then been found in pure ZnO material, GaInP, and carbon nanodots. 7–11 The reason for the negative thermal quenching is mostly attributed to electrons at defect energy states, which couple with phonons and can be easily activated by thermal energy. 3–11…”