Vanadium substitution: A simple and economic way to improve UV sensing in ZnO

Abstract

UV sensing in pure ZnO is due to oxygen adsorption/desorption process from ZnO surface.Vanadium doping improves UV sensitivity of ZnO. Enhancement in UV sensitivity in doped ZnO is attributed to trapping and de-trapping of electrons at V 4+ & V 5+ -related defect states.An extra electron in the V 4+ state is excited under UV illumination while in absence of the same a trapping happens at the V 5+ state. An insight to the mechanism is obtained by an analytic study of the response phenomenon. Introduction:Ultraviolet detection is becoming important nowadays related to various important aspects of science/technology associated with health, environment and even space research [1,2]. Sensitive silicon based UV detectors are already available in market. But these detectors require costly visible light filters as they are sensitive to visible light. Faster, more sensitive, cost-effective UV detection is therefore an important research area. GaN, SiC and diamond are promising candidates[3-5]. But all of these are expensive materials. ZnO is an abundant, inexpensive, non-toxic and environmental friendly material with good thermal/chemical stability and high photoconductivity. UV sensing and response in ZnO, mainly depend on the surface reaction and therefore, surface defects, grain size and oxygen adsorption properties[6-8]. Several morphological studies of ZnO show enhancement in UV sensing. Doping on the other hand modifies electronic, optoelectronic and photoconductive properties of ZnO. Significant modifications have been observed in optoelectronic properties with various types of doping. Vanadium doping is one of the most interesting ones exhibiting luminescence, optoelectronic and photo sensing properties. These properties arise out of electron trapping defect states formation within the bandgap. This study analyses the effect of vanadium doping on UV

Influence of V2O5 and B2O3 addition on the sintering behaviour and physical properties of ZnO ceramics

“…Thus, vanadium (V 4+ or V 5+ ) incorporation can form defect states in between the conduction and valence bands of ZnO [26].…”

“…According to Srivastava et al [26] the valence state of vanadium controls the oxygen content and lattice dimensions. It was reported that both V 4+ and V 5+ ions are more electropositive than Zn 2+ ions.…”

UV Sensitivity of Indium‐Zinc Oxide Nanofibers

“…In vacuum (2.4 × 10 −3 Torr, i.e., 0.4 Pa), the recovery time increases to several tens of minutes [13]. Numerous studies of ZnO show an enhancement in UV sensing due to doping of the material with di erent elements, including indium [5,6], vanadium [14], magnesium [15], aluminum [12,16,17], gallium [17], tin [18], manganese [19], nickel [20], and others. Di erent mechanisms have been proposed to account for these e ects.…”

“…Di erent mechanisms have been proposed to account for these e ects. In particular, the enhancement in UV sensitivity in vanadium-substituted ZnO is attributed to trapping and detrapping of electrons at V 4+ -and V 5+ -related defect states [14]. e enhanced response of Mg-doped ZnO nanoparticles is associated with unpaired electrons added to the photocurrent [15].…”

Синтез Нанонитей Оксида Индия-Цинка И Исследование Их Чувствительности К Ультрафиолетовому Излучению

“…Таким образом, эксперименты в вакууме подтверждают, что уменьшение сопротивления нитей связано с процессами десорбции-адсорбции кислорода с их поверхности. Полученные результаты согласуются с [19] чению за счет легирования различными элементами, такими как индий [13,14], ванадий [20], магний [21], алюминий [18,22,23], галлий [23], олово [24], марганец [25], никель [26]…”