外电场辅助化学气相沉积方法制备网格状β-Ga_2O_3纳米线及其特性研究
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摘要
利用外电场辅助化学气相沉积(CVD)方法,在蓝宝石衬底上制备出了由三组生长方向构成的网格状β-Ga_2O_3纳米线.研究了不同外加电压大小对β-Ga_2O_3纳米线表面形貌、晶体结构以及光学特性的影响.结果表明:外加电压的大小对样品的表面形貌有着非常大的影响,有外加电场作用时生长的β-Ga_2O_3纳米线取向性开始变好,只出现了由三组不同生长方向构成的网格状β-Ga_2O_3纳米线;并且随着外加电压的增加,纳米线分布变得更加密集、长度明显增长.此外,采用这种外电场辅助的CVD方法可以明显改善样品的结晶和光学质量.
Gallium oxide(Ga_2O_3) has five crystalline polymorphs, i.e. corundum(α-phase), monoclinic(β-phase), spinel(γ-phase), bixbite(δ-phase) and orthorhombic(ε-phase). Among these phases, the monoclinic structured β-Ga_2O_3 is the most stable form, and is a ultraviolet(UV) transparent semiconductor with a wide band gap of 4.9 eV. It is a promising candidate for applications in UV transparent electrodes, solar-blind photodetectors, gas sensors and optoelectronic devices. In recent years, one-dimensional(1D) nanoscale semiconductor structures, such as nanowires,nanobelts, and nanorods, have attracted considerable attention due to their interesting fundamental properties and potential applications in nanoscale opto-electronic devices.Numerous efforts have been made to fabricate such devices in 1D nanostructures such as nanowires and nanorods.Comparing with the thin film form, the device performance in the 1D form is significantly enhanced as the surfaceto-volume ratio increases. In order to realize β-Ga_2O_3 based nano-optoelectronic devices, it is necessary to obtain controlled-synthesis and the high-quality β-Ga_2O_3 nanomaterials. According to the present difficulties in synthesizingβ-Ga_2O_3 nanomaterials, in this paper, the grid-like β-Ga_2O_3 nanowires are prepared on sapphire substrates via electric field assisted chemical vapor deposition method.High-purity metallic Ga(99.99%) is used as Ga vapor source. High-purity Ar gas is used as carrier gas. The flow rate of high-purity Ar carrier gas is controlled at 200 sccm. Then, oxygen reactant gas with a flow rate of 2 sccm enters into the system. The temperature is kept at 900℃ for 20 min. The effect of the external electric voltage on the surface morphology, crystal structure and optical properties of β-Ga_2O_3 nanowires are investigated. It is found that the external electric voltage has a great influence on the surface morphology of the sample. The orientation of the β-Ga_2O_3 nanowires grown under the action of an applied electric field begins to improve. Only a grid composed of three different growth directions appears. And with the increase of applied voltage, the distribution of nanowires becomes denser and the length increases significantly. In addition, it is found that the chemical vapor deposition method assisted by this external electric field can significantly improve the crystallization and optical quality of the samples.
Gallium oxide(Ga_2O_3) has five crystalline polymorphs, i.e. corundum(α-phase), monoclinic(β-phase), spinel(γ-phase), bixbite(δ-phase) and orthorhombic(ε-phase). Among these phases, the monoclinic structured β-Ga_2O_3 is the most stable form, and is a ultraviolet(UV) transparent semiconductor with a wide band gap of 4.9 eV. It is a promising candidate for applications in UV transparent electrodes, solar-blind photodetectors, gas sensors and optoelectronic devices. In recent years, one-dimensional(1D) nanoscale semiconductor structures, such as nanowires,nanobelts, and nanorods, have attracted considerable attention due to their interesting fundamental properties and potential applications in nanoscale opto-electronic devices.Numerous efforts have been made to fabricate such devices in 1D nanostructures such as nanowires and nanorods.Comparing with the thin film form, the device performance in the 1D form is significantly enhanced as the surfaceto-volume ratio increases. In order to realize β-Ga_2O_3 based nano-optoelectronic devices, it is necessary to obtain controlled-synthesis and the high-quality β-Ga_2O_3 nanomaterials. According to the present difficulties in synthesizingβ-Ga_2O_3 nanomaterials, in this paper, the grid-like β-Ga_2O_3 nanowires are prepared on sapphire substrates via electric field assisted chemical vapor deposition method.High-purity metallic Ga(99.99%) is used as Ga vapor source. High-purity Ar gas is used as carrier gas. The flow rate of high-purity Ar carrier gas is controlled at 200 sccm. Then, oxygen reactant gas with a flow rate of 2 sccm enters into the system. The temperature is kept at 900℃ for 20 min. The effect of the external electric voltage on the surface morphology, crystal structure and optical properties of β-Ga_2O_3 nanowires are investigated. It is found that the external electric voltage has a great influence on the surface morphology of the sample. The orientation of the β-Ga_2O_3 nanowires grown under the action of an applied electric field begins to improve. Only a grid composed of three different growth directions appears. And with the increase of applied voltage, the distribution of nanowires becomes denser and the length increases significantly. In addition, it is found that the chemical vapor deposition method assisted by this external electric field can significantly improve the crystallization and optical quality of the samples.
引文
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[20]Smith P A,Nordquist C D,Jackson T N,Mayer T S2000 Appl.Phys.Lett.77 1399
[21]Kumar M S,Lee S H,Kim T Y,Kim T H,Song S M,Yang J W,Nahm K S,Suh E K 2003 Solid-State Electron.47 2075
[22]Zong X,Zhu R 2014 Nanoscale 6 12732
[23]Kumar S,Sarau G,Tessarek C,Bashouti M Y,H?hnel A,Christiansen S,Singh R 2014 J.Phys.D:Appl.Phys.47 435101
[2]Feng Q J,Liu J Y,Yang Y Q,Pan D Z,Xing Y,Shi XC,Xia X C,Liang H W 2016 J.Alloys Compd.687 964
[3]Li Y,Tokizono T,Liao M,Zhong M,Koide Y,Yamada I,Delaunay J J 2010 Adv.Funct.Mater.20 3972
[4]Ma H L,Su Q 2014 Acta Phys.Sin.63 116701(in Chinese)[马海林,苏庆2014物理学报63 116701]
[5]Hegde M,Hosein I D,Radovanovic P V 2015 J.Phys.Chem.C 119 17450
[6]Kumar R,Dubey P K,Singh R K,Vaz A R,Moshkalev S A 2016 RSC Adv.6 17669
[7]Miller D R,Akbar S A,Morris P A 2017 Nano-Micro Lett.9 33
[8]Gu Y Y,Su Y J,Chen D,Geng H J,Li Z L,Zhang LY,Zhang Y F 2014 Cryst.Eng.Comm.16 9185
[9]Tang C M,Liao X Y,Zhong W J,Yu H Y,Liu Z W2017 RSC Adv.7 6439
[10]Peng M Z,Zheng X H,Ma Z G,Chen H,Liu S J,He YF,Li M L 2018 Sens.Actuators,B 256 367
[11]Li Y W,Stoica V A,Sun K,Liu W,Endicott L,Walrath J C,Chang A S,Lin Y H,Pipe K P,Goldman R S,Uher C,Clarke R 2014 Appl.Phys.Lett.105 201904
[12]Tsivion D,Schvartzman M,Popovitz B R,Huth P V,Joselevich E 2011 Science 333 1003
[13]Lee S A,Hwang J Y,Kim J P,Jeong S Y,Cho C R2006 Appl.Phys.Lett.89 182906
[14]Kang B K,Mang S R,Lim H D,Song K M,Song Y H,Go D H,Jung M K,Senthil K,Yoon D H 2014 Mater.Chem.Phys.147 178
[15]Park S Y,Lee S Y,Seo S H,Noh D Y,Kang H C 2013Appl.Phys.Express 6 105001
[16]Jangir R,Porwal S,Tiwari P,Mondal P,Rai S K,Srivastava A K,Bhaumik I,Ganguli T 2016 AIP Adv.6035120
[17]Lee S Y,Choi K H,Kang H C 2016 Mater.Lett.176213
[18]Feng Q J,Liang H W,Mei Y Y,Liu J Y,Ling C C,Tao P C,Pan D Z,Yang Y Q 2015 J.Phys.Mater.C 3 4678
[19]Terasako T,Kawasaki Y,Yagi M 2016 Thin Solid Films620 23
[20]Smith P A,Nordquist C D,Jackson T N,Mayer T S2000 Appl.Phys.Lett.77 1399
[21]Kumar M S,Lee S H,Kim T Y,Kim T H,Song S M,Yang J W,Nahm K S,Suh E K 2003 Solid-State Electron.47 2075
[22]Zong X,Zhu R 2014 Nanoscale 6 12732
[23]Kumar S,Sarau G,Tessarek C,Bashouti M Y,H?hnel A,Christiansen S,Singh R 2014 J.Phys.D:Appl.Phys.47 435101