衬底温度和激光强度对PLD制备ZnO薄膜性质影响的研究
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摘要
随着社会发展和科技的进步,人们对具有良好发光性质材料的需求日益增强,相关研究越发深入。氧化锌(ZnO)是一种宽禁带直接带隙半导体材料,属Ⅱ-Ⅵ族化合物,室温下禁带宽度达到3.37eV,激子束缚能达到60meV,理论上可实现室温下的较强紫外受激辐射,在紫外发射器件、紫外激光器件等领域具有广阔的应用前景。同时,ZnO在表面声波器件、透明电极、气体传感器等方面也得到了广泛的应用。
目前,ZnO薄膜的制备方法有很多,比如,溶胶-凝胶法(Sol-gel)、溅射法(Sputtering)、分子束外延生长法(MBE)、原子层外延生长法(ALE)、金属有机物化学气相沉积(MOCVD)、脉冲激光沉积(PLD)等。其中,PLD是近年发展起来的先进的薄膜生长技术,它通过在高真空条件下用高能激光烧蚀ZnO靶材,生成的蒸发物在加热衬底上沉积并最终生长成ZnO晶体薄膜。与其他生长方法相比,PLD具有操作简单、反应过程迅速、能保持制备的薄膜和靶材组分一致、可以在较低温度条件下制备等优点。
本文以PLD作为生长方法,改变衬底温度和脉冲激光强度,在Si(100)衬底上生长了一系列ZnO薄膜,并用X射线衍射(XRD)、光致发光(PL)、共振拉曼(Raman)等测试方法对薄膜的结构和发光特性进行了表征,具体分析并讨论了衬底温度和激光强度对ZnO薄膜相关性质的影响。
With the fast development of society and technology, the needs of good-quality light-emitting materials are more imperative and the researches about these materials are going much deeper than before.
Zinc Oxide (ZnO) is anⅡ—Ⅵcompound wide-band-gap semiconductor with a band gap of 3.37eV and a large exciton binding energy of 60 meV at room temperature. Wide-band semiconductors attract much more attention because of the needs of short-wavelength devices. Theoretically, it can realize stimulated UV emission at RT, which makes it a promising material for using in ultraviolet light-emitting and laser diodes. Meanwhile,it also has been widely used in surface acoustic wave devices,transparent electrodes,sensors and so on.
There are many methods for growing ZnO films, such as sol-gel method, sputtering, molecular beam epitaxy (MBE), atom layer epitaxy (ALE), metal-organic chemical vapor deposition (MOCVD), Pulsed laser deposition (PLD) and so on.
PLD is a newly developed films growth technique which can fabricate high-quality films compared with other techniques, because of its advantages of simple hardware,atomic-layer control obtained by adjusting the laser energy density and repetition rate. In this technique, high density laser ablates the ZnO ceramic target and produces ZnO plume depositing on heated substrate in high vacuum background.
In this paper, ZnO films were prepared on Si (100) substrates at various substrate temperatures and laser energy, and then annealing was conducted.
The films were examined by X-ray diffraction (XRD), Photoluminescence (PL), Raman and Ellipsometry. Through the researches of the structural and optical properties of ZnO films, we analysis and discuss the effects of deposition parameters on the grown ZnO films. The results suggested that high quality ZnO films with highly c-axis oriention can be prepared by PLD.
目前,ZnO薄膜的制备方法有很多,比如,溶胶-凝胶法(Sol-gel)、溅射法(Sputtering)、分子束外延生长法(MBE)、原子层外延生长法(ALE)、金属有机物化学气相沉积(MOCVD)、脉冲激光沉积(PLD)等。其中,PLD是近年发展起来的先进的薄膜生长技术,它通过在高真空条件下用高能激光烧蚀ZnO靶材,生成的蒸发物在加热衬底上沉积并最终生长成ZnO晶体薄膜。与其他生长方法相比,PLD具有操作简单、反应过程迅速、能保持制备的薄膜和靶材组分一致、可以在较低温度条件下制备等优点。
本文以PLD作为生长方法,改变衬底温度和脉冲激光强度,在Si(100)衬底上生长了一系列ZnO薄膜,并用X射线衍射(XRD)、光致发光(PL)、共振拉曼(Raman)等测试方法对薄膜的结构和发光特性进行了表征,具体分析并讨论了衬底温度和激光强度对ZnO薄膜相关性质的影响。
With the fast development of society and technology, the needs of good-quality light-emitting materials are more imperative and the researches about these materials are going much deeper than before.
Zinc Oxide (ZnO) is anⅡ—Ⅵcompound wide-band-gap semiconductor with a band gap of 3.37eV and a large exciton binding energy of 60 meV at room temperature. Wide-band semiconductors attract much more attention because of the needs of short-wavelength devices. Theoretically, it can realize stimulated UV emission at RT, which makes it a promising material for using in ultraviolet light-emitting and laser diodes. Meanwhile,it also has been widely used in surface acoustic wave devices,transparent electrodes,sensors and so on.
There are many methods for growing ZnO films, such as sol-gel method, sputtering, molecular beam epitaxy (MBE), atom layer epitaxy (ALE), metal-organic chemical vapor deposition (MOCVD), Pulsed laser deposition (PLD) and so on.
PLD is a newly developed films growth technique which can fabricate high-quality films compared with other techniques, because of its advantages of simple hardware,atomic-layer control obtained by adjusting the laser energy density and repetition rate. In this technique, high density laser ablates the ZnO ceramic target and produces ZnO plume depositing on heated substrate in high vacuum background.
In this paper, ZnO films were prepared on Si (100) substrates at various substrate temperatures and laser energy, and then annealing was conducted.
The films were examined by X-ray diffraction (XRD), Photoluminescence (PL), Raman and Ellipsometry. Through the researches of the structural and optical properties of ZnO films, we analysis and discuss the effects of deposition parameters on the grown ZnO films. The results suggested that high quality ZnO films with highly c-axis oriention can be prepared by PLD.
引文
[1] A Ashrafi,A Ueta,A Avramescu,et al. Growth and charaeterization of hypothetical zinc blende ZnO films on GaAs (001) substrates with ZnS buffer layers [J]. APPlied Physics Letters,2000,76 (5):550-552.
[2] M H Sukkar,H L Tuller. Colum-bus:Ameriean Ceramic soeiety,1982,7:71.
[3] G D Mahan. Appl Phys,1983,54:3825.
[4] J W Hoffman,I Lauder. Trans Farady Soc,1970,66:2346.
[5] E Ziegler,A Heinrich, H Oppermann,et al. Phys Status Solidi,1981,A 66:635.
[6]孙柏,《PLD技术制备ZnO薄膜及其结构和发光性质研究》[D]:博士学位论文.安徽:中国科学技术大学核技术及应用,2007.
[7] F H Nicoll. Ultraviolet ZnO laser pumped by an electron beam[J]. Applied Physics Letters,1966,9:13-15.
[8] Reynolds D C,Look D C,Jogai B. Optically pumped ultraviolet lasing from ZnO [J]. Solid State Commun,1996,99(12):873-875.
[9] P Zu,Z K Tang,G K L Wang,et al. Ultraviolet spontaneous and stimulated emissions from ZnO microcrystallite thin films at room temperature[J]. Solid State Communication,1997,103(8):4590-463.
[10] H Cao,Y G Zhao,X Liui,et al. Effect of external feedback on lasing in random media[J]. Applied Physics Letters,1999,75(9):1213-1215.
[11] Wiersma D. The smallest random laser[J]. Nature,2000,406(13):132-133.
[12] K Vanhensden, C H Seager, W L Warren, et al. Correlation between photoluminescence and oxygen vacancies in ZnO phosphors[J]. Applied Physics Letters,1996,68(3):403-405.
[13] H J Egelhaaf, D Oelkrug. Luminescence and nonradiative deactivation of excited states involving oxygen defect centers in polycrystalline ZnO [M]. J Cryst.Growth,1996.
[14] Liu M,Kitai A H,Macscher P. Point defect and luminescence centers in zincoxide and zinc oxide doped with manganese[J]. P Mascher.J.Lumin,1992,54 (1) : 352 42 .
[15] B Lin,Z Fu,Y Jia. Appl Phys Lett,2001,79:943.
[16] X M Fan,J S Lian,Z X Guo,et al. Appl Surf Sci,2005,239:176.
[17] X L Guo,H Tabataga and T Kawai. Pulsed laser reactive deposition of P-type ZnO film enhanced by an electron cyclotron resonance source[J]. Journal of Crystal Growth,2001,223(1-2):135-139.
[18] Y W Heo,Y W Kwon,Y Li,et al. P-type behavior in phosphorus-doped(Zn,Mg)O device structures[J]. Applied Physics Letters,2004,84(18):3474-3476.
[19] Y T Zhang,G T Du,H C Zhu,et al. Comparisons of structural and optical properties of ZnO films grown on (0001) sapphire and (0112) sapphire by low- pressure MOCVD[J]. Optical Materials,2004,27(3):399-402.
[20] W I Park,G C Yi,and H M Jang. Metal-organic vapor-phase epitaxial growth and Photoluminescent properties of Zn1-xMgxO(0=x=0.49)thin films [J]. Applied Physics Letters,2001,79(13):2022-2024.
[21] F G Chen,Z Z Ye,W Z Xu,et al. Fabrication of P-type ZnO thin films via MOCVD method by using phosphorus as dopant source[J]. Journal of Crystal Growth,2005,281:458-462.
[22] A Tsukazaki,T Onuma,M Ohtani,etal. Repeated temperature modulation epitaxy for p-type doping and light-emitting diode based on ZnO[J]. Nature Materials,2005,4:42-46.
[23] J Hinze and K Ellmer.In situ measurement of mechanical stress in Polyerystalline Zine-oxide thin films prepared by magnetron sputtering[J].Joumal of Applied Physics,2000,88(5):2443-2450.
[24] H X Li,J Y Wang,H Liu,etal. Sol-gel Preparation of transparent zinc oxide films with highly preferential crystal orientation[J].Vacuum,2004,77:57-62.
[25]马勇,王万录,廖克俊等.真空蒸发法择优定向生长ZnO薄膜[J].光电子技术,2004,24:l-3.
[26] A Dutta and S Basu. Modified CVD growth and characterization of ZnO thinfilms[J].Materials Chemistry and Physics,1993,34:41-45.
[27] Dinescu Maria and Verardi P. ZnO thin film deposition by laser ablation of Zn target in oxygen reactive atmosphere[J]. Applied Surface Science , 1996 (106) :149-153.
[28] Ogasawara M,Shimizu M and Shiosaki T,Preparation of Oxide Thin Films by Laser Ablation [J]. Jpn.J Aply Phy,1992(31):2971-2974.
[29] Cao H, Zhao Y G,Ong H C,et al,Ultraviolet lasing in resonators formed by scattering in semiconductor polycrystalline films[J]. Appl Phys Lett,1998(73): 3656-3658.
[30] Mukherjee P,Cuff J B and Witanachchi S. Plume expansion and stoichiometry in the growth of multi-component thin films using dual-laser ablation[J]. Applied Surface Science,1998(127-129):620-625.
[31] Liang S,Gorla C R,Emanetoglu N,etal. Epitaxial growth of (1120)ZnO on (0112)Al2O3 by metal-organic chemical vapor deposition[J]. Elec Materials, 1998,27(11):L72-L76.
[32] D M Bagnall,Y F Chen,Z Zhu. Optically pumped lasing from ZnO at room temperature [J]. Appl Phys Lett,1997(70):2230.
[33] Z K Tang,G K L Wang,P Yu,et al. High temperature excitonic stimulated emission from ZnO epitaxial layers[J]. Appl Phys Lett,1998,73(8) :1038.
[34] Z K Tang,G K L Wang,Room-temperature ultraviolet laser emission from self-assembled ZnO microcrystallite thin films[J]. Appl Phys Lett,1998(72):3270.
[35] J M Hammer,D J Channin,M T Duffy,et al. Low-loss epitaxial ZnO optical waveguides[J]. Appl Phys Lett,1972(21):358.
[36] Dinghua Bao,Haoshuang Gu,Anxiang Kuang. Sol-gel drived c-axis oriented ZnO thin film[J].Thin Solid Film,1998(312):37-394.
[37] Y Tajahashi,M Kanamori,A Kondoh. Phototconductivity of Ultrathin Zinc Oxide Film[J]. Jpn.J Appl Phys,1994(33):6611.
[38] D H Zhang,D E Brodie. Photoresponse of polycrystalline ZnO films depositedby r.f.bias sputtering[J].Thin Solid Films,1995(261):334.
[39] D H Zhang. Fast Photoresponse and the related change of crystallite barriers for ZnO films deposited by RF sputtering[J].J Phys,1995,28:1273.
[40] YI Alivov,U Ozgur,S Dogan,etal.Photoresponse of n-ZnO/P-SiC heterojunetion diodes grown by Plasma-assisted molecular-beam epitaxy[J].Applied Physics Letters,2005,86(24):1108.
[41] S Liang,H Sheng,Y Liu,et al. ZnO Schottky ultraviolet Photodetectors [J]. Journal of Crystal Growth,2001,225(2-4):110-113.
[42]叶志镇,张银珠,陈汉鸿等,ZnO光电导紫外探测器的制备和特性研究[J].电子学报,2003,31(11):1605-1607.
[43] K Koike,K Hama,I Nakashima,et al. Molecular beam epitaxial growth of wide band gap ZnMgO alloy films on(111)-oriented Si substrate toward UV detector applications[J]. Journal of Crystal Growth,2005,278(l-4):285-292.
[44] M D Whitfield,B Audic,C M Flannery,et al. Diamond Relat.Mater,1999,732.
[45] H Nakahata,A Hachigo,K Higaki,et al. IEEE Trans,UFFC,1995,42:362.
[46] M B Assouar,F Benedic,O Elmazria,et al. Diamond Relat.Mater,2001,10:681.
[47] Y I gasaki,T Naito,K Murakami,et al. Appl.Surf.Sci.,2001,512:169-170.
[48] Y Yoshino,T.Makino,Y Katayama,et al. Vacuum,2000,59:538.
[49] Frans C M. Am Ceram Soc Bull. 1990,69:1959.
[50] S H Seo,W C Shin,J S Park. Thin Solid Films,2002,416(1-2):190-196.
[51] King S L,Gardeniers J G E,Boyd I W. Pulsed-laser deposited ZnO for device applications[J]. Appl.Surface Sci.,1996(96-98):811-818.
[52]范希梅,连建设.沉积温度对ZnO薄膜结构及发光性能的影响[J].《材料热处理学报》,2007,28 (1).
[53] R K Singh,J Narayan. Pulsed-laser evaporation technique for deposition of thin films:Physics and theoretical model[J]. Physical Review B,1990,41(13):8843-8859.
[2] M H Sukkar,H L Tuller. Colum-bus:Ameriean Ceramic soeiety,1982,7:71.
[3] G D Mahan. Appl Phys,1983,54:3825.
[4] J W Hoffman,I Lauder. Trans Farady Soc,1970,66:2346.
[5] E Ziegler,A Heinrich, H Oppermann,et al. Phys Status Solidi,1981,A 66:635.
[6]孙柏,《PLD技术制备ZnO薄膜及其结构和发光性质研究》[D]:博士学位论文.安徽:中国科学技术大学核技术及应用,2007.
[7] F H Nicoll. Ultraviolet ZnO laser pumped by an electron beam[J]. Applied Physics Letters,1966,9:13-15.
[8] Reynolds D C,Look D C,Jogai B. Optically pumped ultraviolet lasing from ZnO [J]. Solid State Commun,1996,99(12):873-875.
[9] P Zu,Z K Tang,G K L Wang,et al. Ultraviolet spontaneous and stimulated emissions from ZnO microcrystallite thin films at room temperature[J]. Solid State Communication,1997,103(8):4590-463.
[10] H Cao,Y G Zhao,X Liui,et al. Effect of external feedback on lasing in random media[J]. Applied Physics Letters,1999,75(9):1213-1215.
[11] Wiersma D. The smallest random laser[J]. Nature,2000,406(13):132-133.
[12] K Vanhensden, C H Seager, W L Warren, et al. Correlation between photoluminescence and oxygen vacancies in ZnO phosphors[J]. Applied Physics Letters,1996,68(3):403-405.
[13] H J Egelhaaf, D Oelkrug. Luminescence and nonradiative deactivation of excited states involving oxygen defect centers in polycrystalline ZnO [M]. J Cryst.Growth,1996.
[14] Liu M,Kitai A H,Macscher P. Point defect and luminescence centers in zincoxide and zinc oxide doped with manganese[J]. P Mascher.J.Lumin,1992,54 (1) : 352 42 .
[15] B Lin,Z Fu,Y Jia. Appl Phys Lett,2001,79:943.
[16] X M Fan,J S Lian,Z X Guo,et al. Appl Surf Sci,2005,239:176.
[17] X L Guo,H Tabataga and T Kawai. Pulsed laser reactive deposition of P-type ZnO film enhanced by an electron cyclotron resonance source[J]. Journal of Crystal Growth,2001,223(1-2):135-139.
[18] Y W Heo,Y W Kwon,Y Li,et al. P-type behavior in phosphorus-doped(Zn,Mg)O device structures[J]. Applied Physics Letters,2004,84(18):3474-3476.
[19] Y T Zhang,G T Du,H C Zhu,et al. Comparisons of structural and optical properties of ZnO films grown on (0001) sapphire and (0112) sapphire by low- pressure MOCVD[J]. Optical Materials,2004,27(3):399-402.
[20] W I Park,G C Yi,and H M Jang. Metal-organic vapor-phase epitaxial growth and Photoluminescent properties of Zn1-xMgxO(0=x=0.49)thin films [J]. Applied Physics Letters,2001,79(13):2022-2024.
[21] F G Chen,Z Z Ye,W Z Xu,et al. Fabrication of P-type ZnO thin films via MOCVD method by using phosphorus as dopant source[J]. Journal of Crystal Growth,2005,281:458-462.
[22] A Tsukazaki,T Onuma,M Ohtani,etal. Repeated temperature modulation epitaxy for p-type doping and light-emitting diode based on ZnO[J]. Nature Materials,2005,4:42-46.
[23] J Hinze and K Ellmer.In situ measurement of mechanical stress in Polyerystalline Zine-oxide thin films prepared by magnetron sputtering[J].Joumal of Applied Physics,2000,88(5):2443-2450.
[24] H X Li,J Y Wang,H Liu,etal. Sol-gel Preparation of transparent zinc oxide films with highly preferential crystal orientation[J].Vacuum,2004,77:57-62.
[25]马勇,王万录,廖克俊等.真空蒸发法择优定向生长ZnO薄膜[J].光电子技术,2004,24:l-3.
[26] A Dutta and S Basu. Modified CVD growth and characterization of ZnO thinfilms[J].Materials Chemistry and Physics,1993,34:41-45.
[27] Dinescu Maria and Verardi P. ZnO thin film deposition by laser ablation of Zn target in oxygen reactive atmosphere[J]. Applied Surface Science , 1996 (106) :149-153.
[28] Ogasawara M,Shimizu M and Shiosaki T,Preparation of Oxide Thin Films by Laser Ablation [J]. Jpn.J Aply Phy,1992(31):2971-2974.
[29] Cao H, Zhao Y G,Ong H C,et al,Ultraviolet lasing in resonators formed by scattering in semiconductor polycrystalline films[J]. Appl Phys Lett,1998(73): 3656-3658.
[30] Mukherjee P,Cuff J B and Witanachchi S. Plume expansion and stoichiometry in the growth of multi-component thin films using dual-laser ablation[J]. Applied Surface Science,1998(127-129):620-625.
[31] Liang S,Gorla C R,Emanetoglu N,etal. Epitaxial growth of (1120)ZnO on (0112)Al2O3 by metal-organic chemical vapor deposition[J]. Elec Materials, 1998,27(11):L72-L76.
[32] D M Bagnall,Y F Chen,Z Zhu. Optically pumped lasing from ZnO at room temperature [J]. Appl Phys Lett,1997(70):2230.
[33] Z K Tang,G K L Wang,P Yu,et al. High temperature excitonic stimulated emission from ZnO epitaxial layers[J]. Appl Phys Lett,1998,73(8) :1038.
[34] Z K Tang,G K L Wang,Room-temperature ultraviolet laser emission from self-assembled ZnO microcrystallite thin films[J]. Appl Phys Lett,1998(72):3270.
[35] J M Hammer,D J Channin,M T Duffy,et al. Low-loss epitaxial ZnO optical waveguides[J]. Appl Phys Lett,1972(21):358.
[36] Dinghua Bao,Haoshuang Gu,Anxiang Kuang. Sol-gel drived c-axis oriented ZnO thin film[J].Thin Solid Film,1998(312):37-394.
[37] Y Tajahashi,M Kanamori,A Kondoh. Phototconductivity of Ultrathin Zinc Oxide Film[J]. Jpn.J Appl Phys,1994(33):6611.
[38] D H Zhang,D E Brodie. Photoresponse of polycrystalline ZnO films depositedby r.f.bias sputtering[J].Thin Solid Films,1995(261):334.
[39] D H Zhang. Fast Photoresponse and the related change of crystallite barriers for ZnO films deposited by RF sputtering[J].J Phys,1995,28:1273.
[40] YI Alivov,U Ozgur,S Dogan,etal.Photoresponse of n-ZnO/P-SiC heterojunetion diodes grown by Plasma-assisted molecular-beam epitaxy[J].Applied Physics Letters,2005,86(24):1108.
[41] S Liang,H Sheng,Y Liu,et al. ZnO Schottky ultraviolet Photodetectors [J]. Journal of Crystal Growth,2001,225(2-4):110-113.
[42]叶志镇,张银珠,陈汉鸿等,ZnO光电导紫外探测器的制备和特性研究[J].电子学报,2003,31(11):1605-1607.
[43] K Koike,K Hama,I Nakashima,et al. Molecular beam epitaxial growth of wide band gap ZnMgO alloy films on(111)-oriented Si substrate toward UV detector applications[J]. Journal of Crystal Growth,2005,278(l-4):285-292.
[44] M D Whitfield,B Audic,C M Flannery,et al. Diamond Relat.Mater,1999,732.
[45] H Nakahata,A Hachigo,K Higaki,et al. IEEE Trans,UFFC,1995,42:362.
[46] M B Assouar,F Benedic,O Elmazria,et al. Diamond Relat.Mater,2001,10:681.
[47] Y I gasaki,T Naito,K Murakami,et al. Appl.Surf.Sci.,2001,512:169-170.
[48] Y Yoshino,T.Makino,Y Katayama,et al. Vacuum,2000,59:538.
[49] Frans C M. Am Ceram Soc Bull. 1990,69:1959.
[50] S H Seo,W C Shin,J S Park. Thin Solid Films,2002,416(1-2):190-196.
[51] King S L,Gardeniers J G E,Boyd I W. Pulsed-laser deposited ZnO for device applications[J]. Appl.Surface Sci.,1996(96-98):811-818.
[52]范希梅,连建设.沉积温度对ZnO薄膜结构及发光性能的影响[J].《材料热处理学报》,2007,28 (1).
[53] R K Singh,J Narayan. Pulsed-laser evaporation technique for deposition of thin films:Physics and theoretical model[J]. Physical Review B,1990,41(13):8843-8859.