氮气压强对PLD制备ZnO薄膜形貌及光电性能的影响
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摘要
研究了氮气压强对脉冲激光沉积(PLD)法制备ZnO薄膜形貌及光电学性能的影响。结果表明,当氮气压强较低时,ZnO薄膜是由尺寸为50 nm的薄片组成;当氮气压强增加后,ZnO薄膜变成多孔状,并且组成ZnO薄膜的颗粒尺寸逐渐减小。在氮气压强为20 Pa以上时,所制备的ZnO薄膜的光致荧光(PL)光谱是由380 nm的带边发光峰和520 nm的缺陷发光峰组成;当氮气压强较低时(5 Pa和2 Pa),ZnO薄膜的PL光谱只有一个位于400 nm或410 nm处的发光峰。电学方面,2 Pa和5 Pa氮气压强下制备的ZnO薄膜的电阻率约为氮气压强为20 Pa和50 Pa下制备样品的104和105倍。研究表明,当氮气压强较低时,Zn离子和O离子具有较大平均自由程和较大平均动能,因此易使N2离子化,可以使部分N离子掺入ZnO晶格中。当氮气压强较高时,Zn离子和O离子平均动能较小,不易使N2离子化,氮难于掺入ZnO晶格中。
The effects of nitrogen pressure on the morphology and photoelectrical properties of ZnO thin films growth by the pulsed laser deposition( PLD) were studied. The results show that ZnO films are composed of slices with size of 50 nm under lower nitrogen deposition pressures. As the nitrogen pressure increasing,the morphology of ZnO films shows porous structure and the size decreases as the nitrogen pressure increasing. The near band gap photoluminescence( PL) peak( 380 nm) and the defect PL peak( 520 nm) were observed in the samples growth under higher nitrogen pressures( above 20Pa). Samples growth under 2 Pa and 5 Pa nitrogen pressure show a distinct PL spectrum with a violet emission centered at about 410 nm and 400 nm,respectively. The resistivity of ZnO thin films growth under 2 Pa and 5 Pa nitrogen pressures are 104 and 105times higher than that of ZnO samples deposition under 20 Pa and 50 Pa nitrogen pressures,respectively. These results indicate that Zn and O ions from the target have large mean free path and large average kinetic energy under the low nitrogen pressure,which can make N2 ionization and the N ion can easily dope into ZnO crystal lattice. Zn and O ions have small average kinetic energy under high nitrogen pressures,which can't make N2 ionization and N ion can't easily dope into the ZnO lattice.
The effects of nitrogen pressure on the morphology and photoelectrical properties of ZnO thin films growth by the pulsed laser deposition( PLD) were studied. The results show that ZnO films are composed of slices with size of 50 nm under lower nitrogen deposition pressures. As the nitrogen pressure increasing,the morphology of ZnO films shows porous structure and the size decreases as the nitrogen pressure increasing. The near band gap photoluminescence( PL) peak( 380 nm) and the defect PL peak( 520 nm) were observed in the samples growth under higher nitrogen pressures( above 20Pa). Samples growth under 2 Pa and 5 Pa nitrogen pressure show a distinct PL spectrum with a violet emission centered at about 410 nm and 400 nm,respectively. The resistivity of ZnO thin films growth under 2 Pa and 5 Pa nitrogen pressures are 104 and 105times higher than that of ZnO samples deposition under 20 Pa and 50 Pa nitrogen pressures,respectively. These results indicate that Zn and O ions from the target have large mean free path and large average kinetic energy under the low nitrogen pressure,which can make N2 ionization and the N ion can easily dope into ZnO crystal lattice. Zn and O ions have small average kinetic energy under high nitrogen pressures,which can't make N2 ionization and N ion can't easily dope into the ZnO lattice.
引文
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[3]Janotti A,Vande Walle C G.Fundamentals of Zinc Oxide as a Semiconductor[J].Rep.Prog.Phys.,2009,72:126501.
[4]朱慧群,李毅,丁瑞钦,等.p-Zn O薄膜及其异质结的光电性质[J].人工晶体学报,2012,41(3):636-641.Zhu H Q,Li Y,Ding R Q,et al.Optical and Electrical Properties of p-type Zn O Thin Films and Heter-junctions[J].Journal of Synthetic Crystals,2012,41(3):636-641(in Chinese).
[5]韩军,张鹏,巩海波,等.生长条件对脉冲激光沉积制备Zn O∶Al薄膜光电性能的影响[J].物理学报,2013,62(21):216102.Han J,Zhang P,Gong H B,et al.Influence of the Growth Conditions on the Transparent Conductive Properties of Zn O:Al Thin Films Grown by Pulsed Laser Deposition[J].Acta Phys.Sin.,2013,62(21):216102.
[6]杨义发,江超.工艺参数对飞秒激光沉积硅基Zn O大面积均匀薄膜性能的影响[J].人工晶体学报,2014,43(3):631-635.Yang Y F,Jiang C.Influence of Process Parameters on the Properties of Large Area Uniformity Zn O Thin Films Deposited on Silicon Substrate by Femtosecond Laser[J].Journal of Synthetic Crystals,2014,43(3):631-635(in Chinese).
[7]曹培江,林传强,曾玉祥,等.氧气流量对脉冲激光沉积Zn O薄膜的形貌及光学性质影响[J].发光学报,2010,31(2):239-242.Cao P J,Lin C Q,Zeng Y X,et al.Influence of Oxygen Flow Rate on the Morphology and the Optical Properties of Thin Zn O Film s Grown by Pulsed Laser Deposition[J].Chinese Journal of Luminescence,2010,31(2):239-242(in Chinese).
[8]Wu K Y,Fang Q Q,Wang W N,et al.On the Origin of an Additional Raman Mode at 275 cm-1in N-doped Zn O Thin Films[J].J.Appl.Phys.,2012,111:063530.
[9]Wu K Y,Fang Q Q,Wang W N,et al.Influence of Nitrogen on the Defects and Magnetism of Zn O∶N Thin Films[J].J.Appl.Phys.,2010,108:063530.
[10]Zeng H B,Cai W P.Violet Photoluminescence From Shell Layer of Zn/Zn O Core-Shell Nanoparticles Induced by Laser Ablation[J].Appl.Phys.Lett.,2006,88:171910.
[11]王兆阳,胡礼中.氧压与Zn O薄膜发光特性关系研究[J].半导体光电,2009,3(4):574-577.Wang Z Y,Hu L Z.Effects of Oxygen Pressure on Optical Properties of Zn O Thin Films[J].Semiconductor Optoelectronics,2009,3(4):574-577(in Chinese).
[12]Limpijumnong S,Li X,Wei S H,et al.Substitutional Diatomic Molecules NO,NC,CO,and:Their Vibrational Frequencies and Effects on Doping of Zn O[J].Appl.Phys.Lett.,2005,86:211910.
[13]Nickel N H,Gluba M A,Defects in Compound Semiconductors Caused by Molecular Nitrogen[J].Phys.Rev.Lett.,2009,103:145501.