Temperature-dependent S-shaped photoluminescence in ZnCdO alloy

Mohanta, Antaryami; Thareja, R. K.

doi:10.1063/1.3391067

Cited by 18 publications

(9 citation statements)

References 20 publications

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“…Figure 2(b) shows the variation of the PL peak energy with temperature which shows anomalous red (T < 100 K)-blue (100 K T 150 K)-red (T > 150 K) shift with increasing temperature similar to the S-shaped dependence observed in alloyed semiconductors due to localized states caused by potential fluctuations on alloying. [23][24][25] However, in the case of an unalloyed semiconductor, the PL peak energy shows monotonic redshift with increasing temperature due to temperature-induced band gap shrinkage in accordance with the Varshni's formula. 26 It is generally believed that in the low-temperature regime of T < 100 K, the redshift is caused by the localized carriers relaxing to the lower-lying localized states prior to recombination due to the fact that the thermal energy of the localized carriers required to overcome the localization potential is insufficient.…”

Section: Sample Information and Experimental Detailssupporting

confidence: 57%

Observation of weak carrier localization in green emitting InGaN/GaN multi-quantum well structure

Mohanta

Wang

Young

et al. 2015

Journal of Applied Physics

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Discrimination of local radiative and nonradiative recombination processes in an InGaN/GaN single-quantum-well structure by a time-resolved multimode scanning near-field optical microscopy Green emitting InGaN/GaN multi-quantum well samples were investigated using transmission electron microscopy, photoluminescence (PL), and time-resolved photoluminescence (TRPL) spectroscopy. Weak carrier localization with characteristic energy of $12 meV due to an inhomogeneous distribution of In in the InGaN quantum (QW) layer is observed. The temperature dependence of the PL peak energy exhibits S-shape phenomenon and is comparatively discussed within the framework of the Varshni's empirical formula. The full width at half maximum of the PL emission band shows an increasing-decreasing-increasing behavior with increasing temperature arising from the localized states caused by potential fluctuations. The radiative life time, s r , extracted from the TRPL profile shows $T 3/2 dependence on temperature above 200 K, which confirms the absence of the effect of carrier localization at room temperature. V C 2015 AIP Publishing LLC.

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Section: Sample Information and Experimental Detailssupporting

confidence: 57%

Observation of weak carrier localization in green emitting InGaN/GaN multi-quantum well structure

Mohanta

Wang

Young

et al. 2015

Journal of Applied Physics

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“…With increasing Cd concentration in ZnCdO, the band gap gradually decreased due to a larger ionic radius of Cd 2+ [ 72 ]. Note that the photoluminescence spectrum of ZnCdO with 50 wt % Cd showed an abnormal red-blue-redshift with increasing temperature [ 73 ]. Based on these investigations, it is easier to find that the photoluminescent behaviour of nanostructured ZnO materials depends on size, morphology, surface defect types and doping of surface impurity as well as preparation methods.…”

Section: Introductionmentioning

confidence: 99%

Organozinc Precursor-Derived Crystalline ZnO Nanoparticles: Synthesis, Characterization and Their Spectroscopic Properties

et al. 2018

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Crystalline ZnO-ROH and ZnO-OR (R = Me, Et, iPr, nBu) nanoparticles (NPs) have been successfully synthesized by the thermal decomposition of in-situ-formed organozinc complexes Zn(OR)2 deriving from the reaction of Zn[N(SiMe3)2]2 with ROH and of the freshly prepared Zn(OR)2 under an identical condition, respectively. With increasing carbon chain length of alkyl alcohol, the thermal decomposition temperature and dispersibility of in-situ-formed intermediate zinc alkoxides in oleylamine markedly influenced the particle sizes of ZnO-ROH and its shape (sphere, plate-like aggregations), while a strong diffraction peak-broadening effect is observed with decreasing particle size. For ZnO-OR NPs, different particle sizes and various morphologies (hollow sphere or cuboid-like rod, solid sphere) are also observed. As a comparison, the calcination of the fresh-prepared Zn(OR)2 generated ZnO-R NPs possessing the particle sizes of 5.4~34.1 nm. All crystalline ZnO nanoparticles are characterized using X-ray diffraction analysis, electron microscopy and solid-state 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The size effect caused by confinement of electrons’ movement and the defect centres caused by unpaired electrons on oxygen vacancies or ionized impurity heteroatoms in the crystal lattices are monitored by UV-visible spectroscopy, electron paramagnetic resonance (EPR) and photoluminescent (PL) spectroscopy, respectively. Based on the types of defects determined by EPR signals and correspondingly defect-induced probably appeared PL peak position compared to actual obtained PL spectra, we find that it is difficult to establish a direct relationship between defect types and PL peak position, revealing the complication of the formation of defect types and photoluminescence properties.

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“…One interesting feature of ZnO is the ability of bandgap engineering by its alloying with CdO ( E g = 2.3 eV) or MgO ( E g ~ 7.7 eV). Namely, bandgap energy of 2.99 eV (Cd y Zn 1− y O, y = 0.07) can be achieved by doping with Cd 2+ , while Mg 2+ increases the bandgap energy to 3.9 eV (Mg x Zn 1− x O, x = 0.33) [ 5 , 6 , 7 ]. ZnO can be used for phosphor applications because of a strong luminescence in the green–white region of the spectrum.…”

Section: Introductionmentioning

confidence: 99%

Trap Exploration in Amorphous Boron-Doped ZnO Films

Chiu

Chiang

2015

Materials

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This paper addresses the trap exploration in amorphous boron-doped ZnO (ZnO:B) films using an asymmetric structure of metal-oxide-metal. In this work, the structure of Ni/ZnO:B/TaN is adopted and the ZnO:B film is deposited by RF magnetron sputtering. The as-deposited ZnO:B film is amorphous and becomes polycrystalline when annealing temperature is above 500 °C. According to the analysis of conduction mechanism in the as-deposited ZnO:B devices, Ohmic conduction is obtained at positive bias voltage because of the Ohmic contact at the TaN/ZnO:B interface. Meanwhile, hopping conduction is obtained at negative bias voltage due to the defective traps in ZnO:B in which the trap energy level is lower than the energy barrier at the Ni/ZnO:B interface. In the hopping conduction, the temperature dependence of I-V characteristics reveals that the higher the temperature, the lower the current. This suggests that no single-level traps, but only multiple-level traps, exist in the amorphous ZnO:B films. Accordingly, the trap energy levels (0.46–0.64 eV) and trap spacing (1.1 nm) in these multiple-level traps are extracted.

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Temperature-dependent S-shaped photoluminescence in ZnCdO alloy

Cited by 18 publications

References 20 publications

Observation of weak carrier localization in green emitting InGaN/GaN multi-quantum well structure

Observation of weak carrier localization in green emitting InGaN/GaN multi-quantum well structure

Organozinc Precursor-Derived Crystalline ZnO Nanoparticles: Synthesis, Characterization and Their Spectroscopic Properties

Trap Exploration in Amorphous Boron-Doped ZnO Films

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