Zinc Oxide Film With High Transparency And High Density Prepared By Spatial Atomic Layer Deposition

Zinc oxide(ZnO)has a wide range of applications as a high performance semico nductor material in fields such as field emission devices,transparent conductive coati ngs,photoluminescent devices and dyesensitised electrode solar cells.However,the a pplication of ZnO in these fields depends on the grain size and surface morphology of ZnO,and for this reason researchers have focused on the preparation of ZnO.In this work,pure ZnO films were prepared by spatial atomic layer deposition(s ALD)on sili con/glass substrates and characterised by X?ray diffraction(XRD),scanning electron microscopy(SEM),X?ray photoelectron spectroscopy(XPS)and Hall(HALL)effect measurement systems to investigate the effects of substrate temperature,annealing an d other factors on the structure,morphology,optical and electrical properties of the fil ms.The effects of substrate temperature and annealing on the structure,morphology,optical and electrical properties of the films were investigated.In order to investigate the effect of substrate temperature on the properties of ZnO thin films,ZnO thin films were prepared at different substrate temperatures(55-135?)and a series of characterisation analyses were investigated.The results reveal that when ZnO was deposited on the borosilicate glass with a refractive index of about1.52,the average transmittance of all samples exceeded 80%in the visible and near-infrared light range,and the resistivity ranged from(3.2-9.0)×10^-3?-cm.The trans-mittance,the band gap and refractive index are largely unaffected by the substrate tem perature,while the resistivity just decreases slightly with increasing substrate tempera ture.The results indicate that the films deposited on substrates at 55?are highly cry stalline,suggesting that this technique provides a broad process window for the depos ition of ZnO films.In order to investigate the effect of annealing temperature on the properties of ZnO films,ZnO was annealed under oxygen and atmospheric atmosphere at annealing temperatures in the temperature range of 300-800?.The changes in oxygen vacancy defects were analysed by a series of tests.The results demonstrate that oxygen vacancy defects can be effectively suppressed by the annealing treatment,particularly in the temperature range of 500-700?;as the annealing temperature increases,the carrier concentration decreases,leading to an increase in film resistivity.Additionally,oxygen atoms segregate to the ZnO/Si interface to form an interfacial oxide layer,leading to oxygen deficiency in the ZnO films at 300-400?and a decrease in the oxygen atom ratio at 500-800?indicating that the annealing treatment also induces higher crystallinity,increases grain size and improves mobility.At 300-700?the refractive index increases with increasing annealing temperature,which may be due to structural relaxation,densification and crystallisation of the films.However,the annealing treatment has little effect on the transmittance of the film due to the low optical loss.This paper illustrates that varying the substrate temperature and annealing temper ature is an effective way to modulate the properties of ZnO films.