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

Abstract

Wide‐bandgap semiconductor nanowires with surface defect emission centers have the potential to be used as sensitive thermometers and optical probes. Here, we show that the green luminescence of multiferroic BiFeO3 (BFO) nanowires shows an anomalous negative thermal quenching (NTQ) with increasing temperatures. The release of trapped carriers from localized surface defect states is suggested as the possible mechanism for the increased green luminescence which was experimentally observed at elevated temperatures. A reasonable interpretation of the photoluminescence (PL) processes in BFO nanowires is achieved, and the activation energies of the PL quenching and thermal hopping are deduced. Negative thermal quenching of BFO nanowires provides a new strategy for optical thermometry at higher temperatures.

Mechanisms of Thermal Quenching of Defect‐Related Luminescence in Semiconductors

“…Yokogawa et al [56] observed a rise of the 2.65 eV blue band in ZnO at temperatures between 180 and 300 K with an activation energy of %0.1 eV and the quenching at higher temperatures with E A % 0.76 eV. Similar behavior of PL was observed for PL in Zn-doped CuAlS 2 , [57] Mg-doped GaN, [58] undoped ZnO, [59] ZnO nanostructures, [60] BiFeO 3 nanowires, [61] and other materials. Shibata [62] suggested that the negative thermal quenching is caused by thermal excitation of electrons from states lying below the initial state of PL transitions.…”

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

“…[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 activation energies of NTQ process ðE 0 q Þ in BFO nanowires were found to be a few times greater for E2 than for E1, E3, and E4.…”

“…Similar to BFO NWs, the lifetime is independent of the temperature change, resembling the static quenching behavior and can be explained in terms of multiple trapping and detrapping process. 15 Temperature sensing based on ratiometric method Since BFO NPs provide multiple emission peaks, a ratiometric approach to luminescence thermometry could be used. Such ratiometric measurements are insensitive to uctuations of excitation source light or other changes in measurement conditions and, therefore, act as self-referencing (i.e., measurements do not have to be referenced with any temperature standard).…”

“…[9][10][11][12] They serve as traps for carriers and hence affect the recombination and transport of charge carriers. [13][14][15][16] Unlike conventional optical thermometry with semiconductors where luminescent signal decreases at high temperatures, we have observed that BFO NPs exhibit an emission-related negative thermal quenching (NTQ), where the photoluminescence intensity increases with temperature. Here, we propose strategy for temperature sensing based on the NTQ mechanism of intrinsic BFO NPs with an excellent performance of thermal sensitivity and resolution.…”

Micro-Area Ferroelectric, Piezoelectric and Conductive Properties of Single BiFeO3 Nanowire by Scanning Probe Microscopy

“…Particularly, one-dimensional semiconductor nanowires (NWs) have been envisioned as a candidate for efficient and small devices [ 21 ]. The BFO NWs have recently been studied extensively in the quest to miniaturize devices, and these studies found that the BFO NWs have highly efficient carrier separation [ 19 ], negative thermal quenching of emission [ 22 ], extraordinary electrostatic response [ 23 ], and remarkably high polarization [ 24 ]. However, most of the research focuses on macroscopic properties and studies on the domain structure of single NW are still lacking.…”