Structural and optical characterization of ZnO and AZO thin films: the influence of post-annealing

Abstract

In the present study, ZnO and Al:ZnO (AZO) thin films were prepared by reactive RF sputtering on quartz substrates at a constant oxygen partial pressure and a typical sputtering power. Films were annealed at different temperatures in argon ambient in the oven to study their various structural and optical properties. It was understood that introducing Al into ZnO structure would affect the ZnO crystalline structure noticeably. It was observed that annealing had great influence on various properties of thin films while ZnO film showed low crystallinity, Al doping into ZnO structure pronounced significant improvement in both crystallinity and particle sizes. It was found that crystal structures, average crystalline sizes, and topology of all thin films were modified enormously by post-annealing. It was shown that films transparency fluctuated by annealing, in which the transparency of AZO thin film annealed at 500°C was much greater than others. Annealing led to decrease optical band gap of all annealed films from 3.31 to 3.26 eV for ZnO and 4 to 3.4 eV for AZO films. Photoluminescence manifested that blue emission in as-deposited film led to two different blue and violet emissions in all AZO and ZnO films. It was identified that the emission intensity of AZO film annealed at 500°C was 12 times more than other ZnO and AZO films.

Influence of doping behavior of Al on nanostructure, morphology and optoelectronic properties of Al Doped ZnO thin film grown on FTO substrate

“…As shown in Fig. 6b the NBE emission can be related to the free exciton recombination near to band gap while the DLE is attributed to the presence of defects in ZnO lattice, such as Zn vacancies, interstitials, and oxygen vacancies [19]. As it can be seen from Fig.…”

“…Hence, it is important to investigate the influence of the dopants on the structural, optical, and electrical properties of ZnO nanostructure prior to employing these materials in practical applications [6,7]. Some researchers are investigated the effect of Al doping value on different properties of ZnO nanostructure grown by different deposition techniques so far, including molecular beam epitaxy [4], hydrothermal method [11], chemical vapor deposition [16], pulsed laser deposition [17], sol-gel process [5], magnetron sputtering [18], electro deposition [19], and spray pyrolysis [4,20]. Among them, spray pyrolysis technique is considered as an inexpensive, reproducible and particularly useful method for the growth of nanostructures on large area substrates at low temperatures.…”

Ohmic contacts on n-type β-Ga2O3 using AZO/Ti/Au

“…26 AZO has been heavily studied for transparent and flexible device applications such as display panels, gas sensors, organic light emitting diodes, and other optoelectronic devices. [27][28][29][30][31][32] In this letter, we report on the use of AZO interlayers in facilitating Ohmic behavior in Ti/Au contacts on n-type, Si implanted β-Ga 2 O 3 . The minimum specific contact resistance of 2.82×10 -5 Ω-cm 2 was achieved after annealing at 400 • C. By sharp contrast, Ti/Au contacts without the AZO did not lead to Ohmic behavior.…”

“…Low temperature annealing further improved the Ohmic behavior, with compliance of 100 mA reached first by the sample annealed at 400 • C. Increasing annealing temperature further did not improve performance. In previous works, annealing above 300 • C has been found to decrease the carrier concentration and electron mobility within the AZO layer [26][27][28][29][30] temperatures and can be seen when comparing the I-V curves of annealing temperatures 400 • C and 600 • C. The TLM data was used to extract the sheet resistance (R S ), specific contact resistance (R C ), and transfer resistance (R T ). A sample output resistance vs. gap size from AZO contact stack annealed at 400 • C is shown in Figure 4, and a strong linear dependence (r 2 = 0.991) is observed.…”

Ag/Tio2 Nano Thin Films Catalyzed Efficient Synthesis of 6-Amino-4-Aryl-3-Methyl-1,4-Dihydropyrano[2,3-C] Pyrazole-5-Carbonitriles At Green Conditions

“…In recent years nano-composite thin films, due to their industrial application, have been studied by many researchers [4][5][6][7] . Ag/TiO 2 nano particles have been widely used in photo electrochemical and photo catalyst applications.…”