Si/NiO异质pn结的光电性能研究
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摘要
利用磁控溅射方法成功制备了Si/NiO异质pn结。实验表明,退火温度升到400℃时,Si/NiO异质结呈现一定的整流特性;600℃退火的Si/NiO异质结呈现很好的整流特性,正向开启电压达到3.5V,-7V时出现漏电流。这可能是因为600℃退火后,样品结晶转好,应力释放,缺陷减少,从而改善了样品的整流特性。这一结果得到了X射线衍射(XRD)、原子显微镜(AFM)和紫外(UV)结果的充分支持。
NiO is a transparent semiconductor oxide with p-type conductivity,having a direct energy gap of3.7eV,with weak absorption bands due to d-d transitions of 3delectron configuration in the visible region.Here,NiO films were prepared on n type Si substrates by magnetron sputtering to form Si/NiO pn heterojunctions.The XRD results show that only one diffraction peak appear for NiO films on Si substrates,which is corresponding to(111)NiO preferred orientation and indicates that NiO belongs to cubic structure.The right shift of(111)NiO peaks indicates the depression of c axis distances,which may result from the relaxation of strain between NiO and Si substrate and the decrease of defects.The transmittances of NiO films have been obviously improved with annealing temperature,which means annealing temperature is benefit to the better crystallization and the decrease of crystal defects,which has been evidenced by AFM pictures.From I-V curves,the electrical properties have changed better when the annealing temperatures increase and the best rectifying property shows in the Si/NiO pn junction annealed at600℃,where the rectification ratio(I(1+7V)/I(-7V))is 12and its Voc arrives to 3.5Vand the leakage current can be observed until the negative voltage reaches-7V.Considering the results of XRD,AFM,UV and I-V,it can be concluded that the increase of annealing temperature is beneficial to the crystal structure and reduces the crystal defect,the increase of transmittance in NiO films and the improvement of the electircal peroperties of Si/NiO pn junctions.
NiO is a transparent semiconductor oxide with p-type conductivity,having a direct energy gap of3.7eV,with weak absorption bands due to d-d transitions of 3delectron configuration in the visible region.Here,NiO films were prepared on n type Si substrates by magnetron sputtering to form Si/NiO pn heterojunctions.The XRD results show that only one diffraction peak appear for NiO films on Si substrates,which is corresponding to(111)NiO preferred orientation and indicates that NiO belongs to cubic structure.The right shift of(111)NiO peaks indicates the depression of c axis distances,which may result from the relaxation of strain between NiO and Si substrate and the decrease of defects.The transmittances of NiO films have been obviously improved with annealing temperature,which means annealing temperature is benefit to the better crystallization and the decrease of crystal defects,which has been evidenced by AFM pictures.From I-V curves,the electrical properties have changed better when the annealing temperatures increase and the best rectifying property shows in the Si/NiO pn junction annealed at600℃,where the rectification ratio(I(1+7V)/I(-7V))is 12and its Voc arrives to 3.5Vand the leakage current can be observed until the negative voltage reaches-7V.Considering the results of XRD,AFM,UV and I-V,it can be concluded that the increase of annealing temperature is beneficial to the crystal structure and reduces the crystal defect,the increase of transmittance in NiO films and the improvement of the electircal peroperties of Si/NiO pn junctions.
引文
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[15]YANG Yi-fa,JIANG Chao.Properties of femtosecond laser deposited ZnO large-area uniform films on Si substrates[J].Journal of Optoelectronics·Laser,2012,(12):2349-2354.杨义发,江超.飞秒激光沉积ZnO/Si大面积均匀薄膜及其特性[J].光电子·激光,2012,(12):2349-2354.
[16]ZHENG Yuan-yu.Ge thin films on Si substrate and thermal annealing effect on their properties[J].Journal of Optoelectronics·Laser,2011,(2):215-218.郑元宇.Si基外延Ge薄膜及退火对其特性的影响研究[J].光电子·激光,2011,(2):215-218.
[17]YANG Zhi-guo.Investigation on the preparation and properties of NiO/ZnO based heterojunction and MgNiO solid solution thin films[D].Zhejiang:Zhejiang University,2011.杨治国.NiO/ZnO基半导体异质结及MgNiO固溶体薄膜的制备与性能研究[D].浙江:浙江大学,2011.
[18]JANG W L,LU Y M,Hwang W S,et al.Point defects in sputtered NiO films[J].Appl.Phys.Lett.,2009,94:062103.
[19]Yang J L,Lai Y S.Effect of heat treatment on the properties of non-stoichiometric p-type nickel oxide films deposited by reactive sputtering[J].Thin Solid Films,2005,488:242-246.
[20]Karpinski A,Ouldhamadouche N,Ferrec A,et al.Optical characterization of transparent nickel oxide films deposited by DC current reactive sputtering[J].Thin Solid Films,2011,519:5767-5770.
[2]Sato H,Minami T,Takata S,et al.Transparent conducting p-type NiO thin films prepared by magnetron sputtering[J].Thin Solid Films,1993,236:27-31.
[3]Kitao M,Izawa K,Urabe K,et al.Preparation and electrochromic properties of RF-sputtered NiOx films prepared in Ar/O2/H2atmosphere[J].Jpn.J.Appl.Phys.,1994,33:6656-6662.
[4]YANG Qing,SHA Jian,MA Xiang-yang,et al.Synthesis of NiO nanowires by a sol-gel process[J].Materials Letters,2005,59(14-15):1967-1970.
[5]Puspharajah P,Radhakrishna S,Arof A K.Transparent conducting lithium-doped nickel oxide thin films by spray pyrolysis technique[J].Journal of Materials Science,1997,32(11):3001-3006.
[6]LI Chang-an.The response speed of nickel hydroxide thin films prepared by pulsed electrodeposition method[J].Journal of Optoelectronics·Laser,1998,300(4):294-296.李长安.脉冲电沉积氧化镍薄膜电致变色速率的研究[J].光电子·激光,1998,300(4):294-296.
[7]Tsai Shu-yi,Hon Min-hsiung,Lu Yang-ming.Fabrication of transparent p-NiO/n-ZnO heterojunction devices for ultraviolet photodetectors[J].Solid-State Electronics,2011,63(1):37-41.
[8]Sta Imen,Jlassi Mohamed,Hajji Massoud.Fabrication and characterization of NiO/ZnO p-n junctions by sol-gel spin coating technique[A].First International Conference on Renewable Energies and Vehicular Technology[C].First International Conference on Renewable Energies and Vehicular Technology,Hammamet Tunisia:IEEE Power&Energy Society PES,2012,113-115.
[9]Eneko Azaceta,Sudam Chavhan,Paola Rossi,et al.NiO cathodic electrochemical deposition from an aprotic ionic liquid:Building metal oxide n-p heterojunctions[J].Electrochimica Acta,2012,71:39-43.
[10]ZHAO Qi-yi,QI Kang-cheng,SHU Wen-li,et al.Effects of Nitrogen Annealing on the Photelectric Characteritic of NiO thin film[J].Chinese Journal of Electron Devices,2012,35(1):11-14.赵启义,祁康成,舒文丽,等.氮气退火对NiO/ZnO:Al薄膜PN结的影响[J].电子器件,2012,35(1):11-14.
[11]LONG Hao,FANG Guo-jia,HUANG Hui-hui,et al.Ultraviolet electroluminescence from ZnO/NiO-based heterojunction light-emitting Diodes[J].Appl Phys Lett,2009,95(1):013509.
[12]Dutta T,Gupta P,Gupta A,et al.Effect of Li doping in NiO thin films on its transparent and conducting properties and its application in heteroepitaxial p-n junctions[J].J.Appl.Phys.,2010,108(8):083715.
[13]ZHANG Qian,CHEN Xi-ming,YANG Bao-he,et al.Effects of Al thin film on the properties of ZnO thin film in(002)ZnO/Al/(100)Si composite structure[J].Journal of Optoelectronics·Laser,2013,(5):935-939.张倩,陈希明,杨保和,等.Al薄膜对(002)ZnO/Al/Si结构基片中ZnO薄膜特性影响的实验研究[J].光电子·激光,2013,(5):935-939.
[14]CAO Yu,ZHANG Jian-jun,LI Tian-wei,et al.High Ge contentμc-SiGe:H thin films and solar cells prepared by RFPECVD[J].Journal of Optoelectronics·Laser,2013,(5):924-929.曹宇,张建军,李天微,等.RF-PECVD法制备高Ge含量微晶Si-Ge薄膜及太阳电池[J].光电子·激光,2013,(5):924-929.
[15]YANG Yi-fa,JIANG Chao.Properties of femtosecond laser deposited ZnO large-area uniform films on Si substrates[J].Journal of Optoelectronics·Laser,2012,(12):2349-2354.杨义发,江超.飞秒激光沉积ZnO/Si大面积均匀薄膜及其特性[J].光电子·激光,2012,(12):2349-2354.
[16]ZHENG Yuan-yu.Ge thin films on Si substrate and thermal annealing effect on their properties[J].Journal of Optoelectronics·Laser,2011,(2):215-218.郑元宇.Si基外延Ge薄膜及退火对其特性的影响研究[J].光电子·激光,2011,(2):215-218.
[17]YANG Zhi-guo.Investigation on the preparation and properties of NiO/ZnO based heterojunction and MgNiO solid solution thin films[D].Zhejiang:Zhejiang University,2011.杨治国.NiO/ZnO基半导体异质结及MgNiO固溶体薄膜的制备与性能研究[D].浙江:浙江大学,2011.
[18]JANG W L,LU Y M,Hwang W S,et al.Point defects in sputtered NiO films[J].Appl.Phys.Lett.,2009,94:062103.
[19]Yang J L,Lai Y S.Effect of heat treatment on the properties of non-stoichiometric p-type nickel oxide films deposited by reactive sputtering[J].Thin Solid Films,2005,488:242-246.
[20]Karpinski A,Ouldhamadouche N,Ferrec A,et al.Optical characterization of transparent nickel oxide films deposited by DC current reactive sputtering[J].Thin Solid Films,2011,519:5767-5770.