Comparative investigation on cation-cation (Al-Sn) and cation-anion (Al-F) co-doping in RF sputtered ZnO thin films: Mechanistic insight

Abstract

Herein, we report a comparative mechanistic study on cation-cation (Al-Sn) and cationanion (Al-F) co-doped nanocrystalline ZnO thin films grown on glass substrate by RF sputtering technique. Through detailed analyses of crystal structure, morphology, microstructure, UV-VIS-NIR absorption, and electrical transport property, the inherent characteristics of the co-doped films were revealed and compared. All the nanocrystalline films retain the hexagonal wurtzite structure of ZnO and show transparency above 90% in the visible and NIR region. As opposed to expectation, Al-Sn (ATZO) co-doped film show no enhanced carrier concentration consistent with the probable formation of SnO 2 clusters supported by the X-ray photoelectron spectroscopy study. Most interestingly, it has been found that Al-F (AFZO) co-doped film shows three times enhanced carrier concentration as compared to Al doped and Al-Sn co-doped films attaining a value of ~910 20 cm-3 due to the respective cation and anion substitution. The carrier relaxation time increases in AFZO while it decreases significantly for ATZO film consistent with the concurrence of the impurity scattering in the latter.

Просветляющие покрытия на основе ZnO, полученные методом электронно-лучевого испарения

“…3 ря на то что содержание олова в пленках с подслоем толщиной 1, 2 и 4 нм незначительно и составляет 0.33, 0.66 и 1.33 об% соответственно, наблюдается заметный прирост поглощения света в пленке при увеличении содержания Sn. При этом на кривых зависимости ко-эффициента пропускания образцов с пленками от длины волны отсутствуют выраженные интерференционные экстремумы, характерные для плотных пленок даже с меньшим, чем у исследованных нами, массовым содержанием материала [24]. Амплитуды отражения всех при-400 500 600 700 800 900 1000 1100 0 веденных на рис.…”

“…Стоит отметить также, что оба элемента, как Al, так и Sn, активно используются в качестве легирующих добавок материала ZnO для увеличения его проводимости. Совместное легирование обоими материалами рассматривалось, например, в работах [24][25][26].…”

Efficacy of Ion Implantation in Zinc Oxide for Optoelectronic Applications: A Review

“…The past decade has seen varying degrees of research effort and pronounced advancements of wide band gap semiconductor-based devices ranging from the solar cells to the blue lasers. − Zinc oxide (ZnO), being a wide band gap II–VI semiconductor, has attracted invigorated interest as an optoelectronic material for numerous applications over more than the last two decades. Lately, this effort has been strengthened in order to have an in-depth understanding of its unique physical properties and to grow high-quality ZnO films and nanocrystals for device applications. − As compared with other wide-gap materials, ZnO has some unique properties and some advantages such as high emission efficiency, visible light transparency, ultraviolet (UV) absorbance sensitivity, nontoxicity which make them to be used in various technological applications such as photoelectrochemical (PEC) water splitting, UV light-emitting diodes (LEDs), photodetectors, solar cells, catalysis, varistors, supercapacitors and gas sensors, and so on. − ZnO is a competitor of GaN, a well-known III–V wide band gap material which is now widely used for commercial production of short-wavelength as well as white-light-emitting devices. − ZnO has many advantages over GaN such as large exciton binding energy of 60 meV, availability of large-size bulk crystals, easy growth of controllable nanostructures, and earth-abundant constituents which create a situation that allows excitation-based lasing action with a very low threshold currents. − In addition to optoelectronic and electronic devices, ZnO has also become a key material for spintronic applications such as spin LEDs, spin-polarized solar cells, and magneto-optical switches. , In spite of the fact that ZnO has many inherent advantages, a control over its inherent defects and dopants is still lacking, which generates an obstacle in realization of practical devices. − From this point of view, ZnO in the form of two-dimensional (2D) thin films or one-dimensional (1D) nanostructures are of great interest to the researchers because these usually exhibit diverse material properties as compared to their corresponding bulk crystals because of the modified defect state, lattice imperfection, structural disorder, high surface area, exotic polar topology, and so on. − Moreover, compared with conventional devices, nanodevices based on thin films or nanostructures of ZnO have advantageous properties like ultrahigh speed as well as frequency, l...…”

Synergy effects of Al-V-co-doping and oxygen reactive sputtering on electrical and optical properties of ZnO films

“…26) For further improvement of the properties, co-doping of metal elements is considered as a solution, and control of defect generation and suppression are important factors. 27) So far, the effects of aluminum and vanadium co-doping engender conductivity and transmittance, however, the effects are limited to specific substrates and it needs to be generalized. 19,28) Here, we investigate the effects of defect generation and suppression through the oxygen contained reactive RF magnetron sputtering method at low temperature on the electrical conductivity and optical transmittance.…”