Variation of Oxygen Vacancy Defects in sALD-ZnO Films Annealed in an Oxygen-Rich Ambient

Abstract

Oxygen vacancy defects play an important role in determining the properties of zinc oxide (ZnO) film. In this study, ZnO film prepared by a high-deposition-rate spatial ALD process was annealed in an oxygen-rich ambient. The variation of oxygen vacancy defects was analyzed. The results show that oxygen vacancy defects were suppressed by the annealing treatment, particularly at 500 °C–700 °C. As a result, the carrier concentration decreases with increasing annealing temperature, leading to the higher film resistivity. In addition, the oxygen atoms segregated to the ZnO/Si interface to form an interfacial oxide layer, leading to an oxygen-deficient ZnO film when annealed at 300 °C–400 °C and the decrease of oxygen atomic ratio when annealed at 500 °C–800 °C. The annealing treatment also induces higher crystallinity with larger crystallite size, leading to a higher mobility. The refractive index increases with annealing temperature at 300 °C–700 °C, possibly due to the structural relaxation, densification and crystallization of the film. However, the annealing treatment has little effect on the film transmittance due to the low optical loss.

Atomic-layer-deposited Al-doped zinc oxide as a passivating conductive contacting layer for n+-doped surfaces in silicon solar cells

“…Compared to the sample annealed at 400 o C, the individual ZnO:Al grains are much easier to discern and appear columnar. Therefore, it appears that the ZnO grains have coarsened, similar as to what has been reported for spatial ALD-prepared ZnO layers annealed at similar temperatures [82]. Interestingly, for this sample the distinct Al dopant planes could no longer be observed.…”

Carrier tuning of 2D electron gas in field-effect devices based on Al2O3/ZnO heterostructures

“…23 These results suggest that more V O and Zn 0–1+ species are induced and distributed in the interface region of Al 2 O 3 /ZnO, which supports the redox reaction mechanism for the 2DEG origin. 16,24 The surface of the ZnO underlayer is chemically reduced during the Al 2 O 3 deposition, generating V O as donors and free electrons moving parallel to the interface direction.…”

Indium-free GZO thin films prepared using plasma-enhanced atomic layer deposition: toward thin film transistor application

“…The decline and disappearance of the (002) peak may have contributed to the rise in film resistivity. 59 It also indicates that the Ga 2 O 3 cycle ratio can be changed in order to get the desired electrical properties. In the present study, the GZO sample with 7.5% Ga 2 O 3 cycle ratio shows potential as a promising candidate for a TFT channel layer.…”