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DFT Study of the Effect of Temperature on ZnO Adsorbed on α-Al2O3(0001) Surface
Chun Yang* ,Yi Yu ,Lai-cai Li
Author NameAffiliationE-mail
Chun Yang* Key Lab of Computer Software, College of Material and Chemistry, Sichuan Normal University, Chengdu 610068, China yangc@263.net  
Yi Yu Key Lab of Computer Software, College of Material and Chemistry, Sichuan Normal University, Chengdu 610068, China  
Lai-cai Li Key Lab of Computer Software, College of Material and Chemistry, Sichuan Normal University, Chengdu 610068, China  
Abstract:
The adsorption and the growth of ZnO on α-Al2O3(0001) surface at various temperatures were theoretically calculated by using a plane wave pseudopotentials (USP) method based on density functional theory.The average adsorption energy of ZnO at 400, 600 and 800 ℃ is 4.16±0.08, 4.25±0.11 and 4.05±0.23 eV respectively. Temperature has a remarkable effect on the structure of the surface and the interface of ZnO/α-Al2O3(0001). It is found that the Zn-hexagonal symmetry deflexion does not appear during the adsorption growth of ZnO at 400 ℃, and that the ZnO[10-10] is parallel with the [10-10] of the α-Al2O3(0001), which is favorable for forming ZnO film with the Zn-terminated surface. It is observed from simulation that there are two kinds of surface structures in the adsorption of ZnO at 600 ℃: one is the ZnO surface that has the Zn-terminated structure, and whose [10-10] parallels the [10-10] of the substrate surface, and the other is the ZnO[10-10] //sapphire [11-10] with the O-terminated surface. The energy barrier of the phase transition between these two different surface structures is about 1.6 eV, and the latter is more stable. Therefore,the suitable temperature for the thin film growth of ZnO on sapphire is about 600 ℃, and it facilitates the formation of wurtzite structure containing Zn-O-Zn-O-Zn-O double-layers as a growth unit-cell. At 600 ℃, the average bond length of Zn-O is 0.190±0.01 nm, and the ELF value indicates that the bond of (substrate)-O-Zn-O has a distinct covalent character, whereas the (Zn)O-Al (substrate) shows a clear character of ionic bond. However, at a temperature of 800 ℃, the dissociation of Al and O atoms on the surface of the α-Al2O3(0001) leads to a disordered surface and interface structure. Thus, the Zn-hexagonal symmetry structure of the ZnO film is not observed under this condition
Key words:  ZnO, α-Al2O3(0001) surface, Adsorption, Density functional calculations
FundProject:
温度对α-Al2O3(0001)表面吸附生长ZnO影响的DFT研究
杨春*,余毅,李来才
摘要:
用密度泛函理论的平面波赝势法对ZnO在α-Al2O3(0001)表面吸附生长进行了动力学计算.400、600、800℃时,平均每个ZnO的吸附能分别为4.16±0.08、4.25±0.11、4.05±0.23 eV.温度对ZnO/α-Al2O3(0001)界面有显著影响.400℃的ZnO的吸附生长中未出现Zn六角对称的偏转,计算得到ZnO[10-1]明显平行于基片[10-10],该温度有利于最外层为Zn原子的薄膜表面.600℃的ZnO吸附生长过程中存在两种表面结构,一种是表面原子终止于Zn,ZnO薄膜[1
关键词:  密度泛函理论  吸附生长  ZnO薄膜  α-Al2O3
DOI:10.1360/cjcp2006.19(2).137.6
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