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Contactless Optical Characterization of Carrier Dynamics in Free-Standing InAs-InAlAs Core-Shell Nanowires on Silicon
摘要： Contactless time-resolved pump-probe and external quantum efficiency measurements were performed on epitaxially grown free-standing wurtzite indium arsenide/indium aluminum arsenide (InAs-InAlAs) core-shell nanowires on Si (111) substrate from 77K to 293K. The first independent investigation of Shockley-Read-Hall, radiative and Auger recombination in InAs-based NWs is presented. Although the Shockley-Read Hall recombination coefficient was found to be at least two orders of magnitude larger than the average experimental values of other reported InAs materials, the Auger recombination coefficient was reported to be ten-fold smaller. The very low Auger and high radiative rates result in an estimated peak internal quantum efficiency of the core-shell nanowires as high as 22% at 77K, making these nanowires of potential interest for high efficiency mid-infrared emitters. A greater than two-fold enhancement in minority carrier lifetime was observed from capping nanowires with a thin InAlAs shell due to passivation of surface defects.
关键词： Auger recombination rate,radiative,Shockley-Read-Hall,Pump-probe spectroscopy,core-shell nanowires,surface/interface recombination velocity,minority carrier lifetime
更新于2025-09-23 15:23:52
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Facile Synthesis of g-C3N4/CdWO4 with Excellent Photocatalytic Performance for the Degradation of Minocycline
摘要： A novel g-C3N4/CdWO4 composite was formed by hydrothermal process and utilized for the removal of Minocycline (MC) antibiotic under visible light exposure. The XRD patterns of synthesized sample reveal the pure crystalline structure and phase of g-C3N4/CdWO4. The SEM images of g-C3N4/CdWO4 showed regular short rod structure with diameter in the range of 20-60 nm. These images also showed that the g-C3N4/CdWO4 structure has well contacted surfaces which enhanced the interfacial transfer of charge as a result of which the performance of photocatalyst was improved. The energy dispersive spectroscopy (EDS) images of g-C3N4, CdWO4 and g-C3N4/CdWO4 conclude that there were no impurities in the synthesized samples. SEM and EDS results confirm the interface interaction develop between g-C3N4 and CdWO4 due to hybridization. The FTIR spectrum of composite showed that the composite formed had extensively conjugated system and the band gap energies calculated for CdWO4, g-C3N4 and g-C3N4/CdWO4 were 3.31 eV, 2.67 eV and 2.71 eV respectively. A remarkable drop in photoluminescence intensity of g-C3N4/CdWO4 was observed as compared to pure g-C3N4 and CdWO4 which led to lower recombination rate of photo-induced charge carriers and hence a higher photocatalytic performance for the degradation of minocycline under visible-light irradiation.
关键词： Photocatalytic Performance,Photocatalyst,Recombination Rate,Charge Carries,minocycline
更新于2025-09-23 15:22:29
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Effect of Doping on the Luminescent Properties of LED Heterostructures with Quantum Wells
摘要： It is established that the model of interband radiative recombination in a semiconductor under bipolar injection of charge carriers, in which the recombination rate is described by the product of the total charge carrier concentrations, does not take into account the imbalance in the concentrations of recombining particles physically existing during doping. To calculate the number of electron-hole pair recombination events taking into account the difference in the concentrations of recombining particles, it is proposed to use the calculation of the reciprocal sum of the reciprocal concentrations using the participation functions. It is shown that at such a description of the number of recombination events, an increase in the doping impurity concentration reduces the number of events, but leaves the radiative recombination time unchanged at any injection level.
关键词： emission of radiation,radiative recombination rate,participation functions
更新于2025-09-23 15:21:01
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Alternative buffer layers in Sb2Se3 thina??film solar cells to reduce opena??circuit voltage offset
摘要： Antimony Selenide (Sb2Se3) thin-film solar cell configurations with alternative buffer layers are proposed to improve the efficiency by minimizing open‐circuit voltage offset (Voc,offset). The conduction band offsets have been optimized not only at absorber/buffer (ΔEC‐BA) but also at buffer/transparent conductive oxide (ΔEC-TB). Voltage‐independent recombination rates in the quasi‐neutral region (Rb0), and at the absorber/buffer interface (Ri0) of the Sb2Se3 solar cells with various configurations are individually modelled. The development of cell configurations causes to decrease the Ri0, and Rb0, consequently reducing the Voc,offset. It is found that the solar cell configuration of Mo/MoSe2/Sb2Se3/TiO2/ZnO0.4S0.6/Zn0.93Mg0.07O/ZnO:Al is suitable with the ΔEC‐BA of 0.29 eV and ΔEC‐TB of ?0.2 eV, therefore considerably reducing Voc,offset to approximately 0.52 V, and improving the efficiency to 15.46%.
关键词： Recombination rate,Sb2Se3,Open‐circuit voltage offset,Device configuration,Alternative buffer layers
更新于2025-09-23 15:21:01
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Laser-Tuned Large Photo Hall Effect in p-Type Silicon Based on Surface States
摘要： The photo Hall e?ect (PHE) has attracted much attention for a long time due to its broader application in photosensitive semiconductor devices. In this paper, we show a PHE observed in p-type silicon induced by pointolite irradiation, which di?ers from the conventional PHE caused by a surface light source. The Hall voltage is improved by 63 times when a laser is applied at the edge of the sample, and it presents good position-sensitive properties when the laser spot moves along the middle line of the sample. An ultra-broadband spectral responsivity is observed from 405 to 980 nm at 150?300 K. The experimental result shows that the laser-induced photo Hall voltage is not the simple superposition of photo current and dark current. Interestingly, this PHE can be greatly deteriorated when the surface state is destroyed and partially replaced by a Schottky barrier via covering with a thin Ag nano?lm. We attribute this phenomenon to the surface band bending caused by charged surface states. Compared with the traditional PHE, this laser-induced, position-sensitive, large-tuned-range e?ect based on surface states provides a di?erent approach to reveal the transmission properties of local unevenly distributed non-balanced carriers and can be used to design light-sensitive Hall devices.
关键词： photo Hall e?ect,surface states,recombination rate,magnetic ?eld,Schottky barrier
更新于2025-09-19 17:13:59
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Model for electroluminescence in single-walled carbon nanotube field effect transistor under transverse magnetic field
摘要： Electroluminescence spectrum and radiative recombination rate of short channel single-walled carbon nanotube field effect transistor in presence of transverse magnetic field is calculated by using non-equilibrium Green’s function method. Significant enhancement in radiative recombination rate and red shift in electroluminescence spectrum are observed with increase in the strength of magnetic field. The band gap suppression estimated from energy position resolved local density of states calculation plays a dominant role in transport mechanism under the influence of external magnetic field. The tuning of electroluminescence spectrum of single-walled carbon nanotube by transverse magnetic field can be employed as nanoscale optical source in next generation optoelectronic and photonic devices.
关键词： electroluminescence,single-walled carbon nanotube,optoelectronics,radiative recombination rate,plasmonics,field effect transistor
更新于2025-09-16 10:30:52
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Aging Effect of a Cu(In,Ga)(S,Se) <sub/>2</sub> Absorber on the Photovoltaic Performance of Its Cd‐Free Solar Cell Fabricated by an All‐Dry Process: Its Carrier Recombination Analysis
摘要： Cd-free Cu(In,Ga)(S,Se)2 (CIGSSe) solar cells are fabricated by an all-dry process (a Cd-free and all-dry process CIGSSe solar cell) with aged CIGSSe thin film absorbers. The aged CIGSSe thin films are kept in a desiccator cabinet under partial pressure of oxygen of ≈200 Pa for aging time up to 10 months. It is reported for the first time that aged CIGSSe thin film with increased aging time results in significant enhancement of photovoltaic performance of Cd-free and all-dry process CIGSSe solar cells, regardless of the alkali treatment. Based on carrier recombination analysis, carrier recombination rates at the interface and in the depletion region of the Cd-free and all-dry process CIGSSe solar cells are reduced owing to avoidance of sputtering damage on CIGSSe absorber surface, which is consistent with the strong electron beam-induced current signal near CIGSSe surface after the increased aging time. It is implied that the interface and near-surface qualities are clearly improved through the increased aging time, which is attributable to the self-forming of Inx(O,S)y near CIGSSe surface, which acts as a buffer layer. Ultimately, the 22.0%-efficient Cd-free CIGSSe solar cell fabricated by all-dry process is achieved with the aged Cs-treated CIGSSe absorber with the aging time of 10 months.
关键词： all-dry process,EBIC measurements,Cd-free Cu(In,Ga)(S,Se)2 solar cells,aging time,carrier recombination rate
更新于2025-09-11 14:15:04