| Zinc oxide(ZnO) is a wide and direct band gap semiconductor material and it has received considerable attention in recent years. The main advantages of ZnO compared with ITO are nontoxic, inexpensive, and more stable in reducing ambient. An n-type conductivity of ZnO can be increased by doping with trivalent atom, such as aluminum(Al), gallium, or indium. Among these materials, Al-doped ZnO(AZO) has been considered as a suitable electrode for optoelectronic devices owing to its lowest resistivity and excellent optical transparency in the visible and NIR regions. AZO has been used as the anode for organic light-emitting diodes and organic solar cells. However, it has not been used in organic photodetectors what we know so far. ALD is a very promising deposition technique for semiconductor films since it has several practical advantages including accurate and simple thickness control, large area and large batch capability, good conformality and reproducibility. The films prepared by ALD are usually dense, pinhole-free, and extremely conformal to the underlying substrate. Recently, ALD technology has been employed to grow transparent conductive AZO films with resistivity as low as in the order of 10-4 Ω?cm.In this work, Diethylzinc((C2H5)2Zn, DEZn) and tri-methyl aluminum(Al(CH3)3, TMA) were used as the metal precursors for ZnO and Al2O3, respectively, while water vapour was used as the oxidant. The Al concentrations of the AZO film are1%, 2% and 3%, respectively. The thickness of the AZO films was about 200 nm. The optical properties and crystal structure of the samples were characterized by photoluminescence(PL), ultraviolet-visible(UV-vis) absorption spectra, X-ray diffraction(XRD), The resistivity, carrier density, and motility of the films were measured by Hall effect measurement. More important, The NIR-PDs were fabricated on AZO substrates successed, it is prove that AZO film grown by ALD maybe replace ITO film. |
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