MIS结构InGaN电流传输机制及金属纳米颗粒的自组装研究
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摘要
GaN基半导体的能带带隙从0.7eV至6.2eV连续可调,所对应的波长覆盖了近红外到紫外光谱范围,基于该材料体系的探测器有望在火警、导弹预警等领域得到广泛的应用。近年来高In、Al组分的InGaN、AlGaN材料,由于生长技术不成熟,材料缺陷密度高,传统工艺制备的器件达不到理想的效果。因此,需要研究新的工艺来提高器件的性能。等离子体(Plasmon)技术已经在发光二级管(LED)中广泛应用,该技术也可用来提高光电探测器的光普响应度。金属纳米颗粒的研究已成为了当前人们研究的热点领域之一。
本论文针对InGaN材料高密度的表面态,尝试用MIS结构来提高肖特基势垒,减小漏电流,并对MIS结构器件电流输运机制进行了分析。同时,在p-AlGaN表面采用金属薄膜自组装生成了不同尺寸的纳米颗粒,并以此作为模板通过刻蚀将p-AlGaN表面制备成纳米柱的表面形貌并进行了光学性能的。论文的主要研究成果如下：
1.采用不同的绝缘层技术制备了金属-绝缘体-半导体(MIS)结构的InGaN探测器。研究发现,空间电荷限制的电流是MIS结构InGaN探测器的一个主要的漏电流机制：对具有采用原子层淀积(ALD)方法制备的Al2O3绝缘层结构的探测器,绝缘层中缺陷密度较少,缺陷能级呈高斯分布；但对具有采用PECVD方法生长的Si3N4绝缘层结构的探测器,绝缘层中缺陷密度大,呈指数分布,并且伴随有双边的Fowler-Nordheim遂穿效应。同时,Al2O3绝缘层结构的探测器光电响应度是Si3N4绝缘层结构探测器的3倍,主要原因是由于Si3N4绝缘层中存在大量缺陷,这些缺陷俘获了大量的电子,而电子作为空穴陷阱,会俘获探测器光电流产生的自由空穴,从而降低了光电响应。
2.分别采用Al、Au、Ni三种金属薄膜自组装制备了纳米颗粒。研究发现,退火温度越高,时间越短,对应的纳米颗粒越大。另外,颗粒大小还与金属有关,发现同样制备工艺条件下,Ni金属颗粒尺寸最大,Al金属颗粒尺寸最小。同时,XPS电子能谱测试显示退火后的金属颗粒与AlGaN层发生了界面反应,生成了金属间化合物。
3.基于金属纳米颗粒模板,通过刻蚀在p-AlGaN表面制备出了纳米柱结构的表面形貌,光致发光谱测试结果显示p-AlGaN材料的发光强度增强了好几个数量级,纳米柱样品采用KOH溶液清洗后,发光强度会进一步增强。
The band gap of GaN-based semiconductor is continuously adjustable from0.7eV to6.2eV, which is corresponding to wavelength range from near-infrared to ultraviolet. The detectors based GaN material is expected to be widely used in fire, missile warning, and other fields. In recent years people have been working on InGaN and AlGaN materials with high In or Al content, but it is difficult to get high quality crystal due to high density of defects in materials. Devices prepared by traditional processes do not meet the requirement. So we should develop new processes. Plasma technology has been widely used in the light emitting diode (LED), and the technology also can be used to improve the performances of the photodetector. The application of metal nanoparticle in the photodetector has attracted wide attention.
In order to reduce the influence of the high density of surface states on the InGaN photodetectors, we employed the metal-insulator-semiconductor (MIS) structure to improve Schottky barrier and reduce leakage current. Moreover, the metal nanoparticles were fabricated through self-assembled method. The main research results are as follows:
1) The current transport mechanisms and photoelectric responsivity of InGaN MIS photodetectors with Si3N4and Al2O3insulating layers deposited by plasma-enhanced chemical vapor deposition and by atomic layer deposition, respectively, were investigated. The results show that the space-charge-limited current (SCLC) mechanism is a dominant leakage conduction mechanism in the InGaN MIS photodetectors. The SCLC mechanism is mediated by an exponential trap distribution, and a bi-directional Fowler-Nordheim tunneling effect is observed in the metal-Si3N4-InGaN photodetector. The metal-Si3N4-InGaN photodetector has a far lower photoelectric responsivity than the metal-A12O3-InGaN photodetector. In the Si3N4bulk, a higher trap-state density exists with an exponential distribution, and therefore the electrons that are injected from the metal under reverse bias are easier to capture by these acceptor-like traps, which leads to the formation of a trapped electron space charge. These trapped electrons act as hole traps and they tend to capture the photogenerated free holes from the InGaN semiconductor. Therefore, this trapping process increases the probability of the recombination of photogenerated carriers in the bulk of the dielectrics and at the interface of the dielectric-InGaN and hence decreases the photoelectric responsivity.
2) Nanoparticles were prepared by self-assembly with three different metal thin films of Al, Au and Ni. The studies found that the higher annealing temperature and the shorter annealing time, the larger metal nanoparticles. In addition, the particle size is related with the metal itself. The particle size of Ni is biggest whilst the particle size of Al is smallest under the same fabricating conditions. XPS electron spectroscopy results show that the interface reaction between the metal particles and AlGaN surface happened after annealing and the new intermetallic compound was generated.
3) Then a nanorod structure is prepared by etching AlGaN surface using metal nanoparticles as template. The result of PL measurement shows that the luminous intensity of nanorod structural p-AlGaN increases several orders of magnitude and be further enhanced after the cleaning of KOH solution.
本论文针对InGaN材料高密度的表面态,尝试用MIS结构来提高肖特基势垒,减小漏电流,并对MIS结构器件电流输运机制进行了分析。同时,在p-AlGaN表面采用金属薄膜自组装生成了不同尺寸的纳米颗粒,并以此作为模板通过刻蚀将p-AlGaN表面制备成纳米柱的表面形貌并进行了光学性能的。论文的主要研究成果如下：
1.采用不同的绝缘层技术制备了金属-绝缘体-半导体(MIS)结构的InGaN探测器。研究发现,空间电荷限制的电流是MIS结构InGaN探测器的一个主要的漏电流机制：对具有采用原子层淀积(ALD)方法制备的Al2O3绝缘层结构的探测器,绝缘层中缺陷密度较少,缺陷能级呈高斯分布；但对具有采用PECVD方法生长的Si3N4绝缘层结构的探测器,绝缘层中缺陷密度大,呈指数分布,并且伴随有双边的Fowler-Nordheim遂穿效应。同时,Al2O3绝缘层结构的探测器光电响应度是Si3N4绝缘层结构探测器的3倍,主要原因是由于Si3N4绝缘层中存在大量缺陷,这些缺陷俘获了大量的电子,而电子作为空穴陷阱,会俘获探测器光电流产生的自由空穴,从而降低了光电响应。
2.分别采用Al、Au、Ni三种金属薄膜自组装制备了纳米颗粒。研究发现,退火温度越高,时间越短,对应的纳米颗粒越大。另外,颗粒大小还与金属有关,发现同样制备工艺条件下,Ni金属颗粒尺寸最大,Al金属颗粒尺寸最小。同时,XPS电子能谱测试显示退火后的金属颗粒与AlGaN层发生了界面反应,生成了金属间化合物。
3.基于金属纳米颗粒模板,通过刻蚀在p-AlGaN表面制备出了纳米柱结构的表面形貌,光致发光谱测试结果显示p-AlGaN材料的发光强度增强了好几个数量级,纳米柱样品采用KOH溶液清洗后,发光强度会进一步增强。
The band gap of GaN-based semiconductor is continuously adjustable from0.7eV to6.2eV, which is corresponding to wavelength range from near-infrared to ultraviolet. The detectors based GaN material is expected to be widely used in fire, missile warning, and other fields. In recent years people have been working on InGaN and AlGaN materials with high In or Al content, but it is difficult to get high quality crystal due to high density of defects in materials. Devices prepared by traditional processes do not meet the requirement. So we should develop new processes. Plasma technology has been widely used in the light emitting diode (LED), and the technology also can be used to improve the performances of the photodetector. The application of metal nanoparticle in the photodetector has attracted wide attention.
In order to reduce the influence of the high density of surface states on the InGaN photodetectors, we employed the metal-insulator-semiconductor (MIS) structure to improve Schottky barrier and reduce leakage current. Moreover, the metal nanoparticles were fabricated through self-assembled method. The main research results are as follows:
1) The current transport mechanisms and photoelectric responsivity of InGaN MIS photodetectors with Si3N4and Al2O3insulating layers deposited by plasma-enhanced chemical vapor deposition and by atomic layer deposition, respectively, were investigated. The results show that the space-charge-limited current (SCLC) mechanism is a dominant leakage conduction mechanism in the InGaN MIS photodetectors. The SCLC mechanism is mediated by an exponential trap distribution, and a bi-directional Fowler-Nordheim tunneling effect is observed in the metal-Si3N4-InGaN photodetector. The metal-Si3N4-InGaN photodetector has a far lower photoelectric responsivity than the metal-A12O3-InGaN photodetector. In the Si3N4bulk, a higher trap-state density exists with an exponential distribution, and therefore the electrons that are injected from the metal under reverse bias are easier to capture by these acceptor-like traps, which leads to the formation of a trapped electron space charge. These trapped electrons act as hole traps and they tend to capture the photogenerated free holes from the InGaN semiconductor. Therefore, this trapping process increases the probability of the recombination of photogenerated carriers in the bulk of the dielectrics and at the interface of the dielectric-InGaN and hence decreases the photoelectric responsivity.
2) Nanoparticles were prepared by self-assembly with three different metal thin films of Al, Au and Ni. The studies found that the higher annealing temperature and the shorter annealing time, the larger metal nanoparticles. In addition, the particle size is related with the metal itself. The particle size of Ni is biggest whilst the particle size of Al is smallest under the same fabricating conditions. XPS electron spectroscopy results show that the interface reaction between the metal particles and AlGaN surface happened after annealing and the new intermetallic compound was generated.
3) Then a nanorod structure is prepared by etching AlGaN surface using metal nanoparticles as template. The result of PL measurement shows that the luminous intensity of nanorod structural p-AlGaN increases several orders of magnitude and be further enhanced after the cleaning of KOH solution.
引文
[1]L. Liu, H. H. Edgar, Mater. Sci. Eng. R 37,61 (2002).
[2]S. D. Lester, F. A.Ponce, M. G. Craford, and D. A. Steigerwald, Appl Phys. Lett. 661249(1995)
[3]F. Fichter and Z. Anorg, Chem.54,322(1907).
[4]R. Juza, and H. Hahn, Zeitschrift fur anorganische und allgemeine Chemie, 239,282(1938).
[5]H. P. Maruska, and J. J. Tietjen, Appl. Phys. Lett.15,327(1969).
[6]J. I. Pankove, E. A. Miller, and J. E. Berkeyheiser, RCA review 32,383(1971).
[7]H. P. Maruska, W. C. Rhines, and D. A. Stevenson, Mater. Res. Bull.7, 777(1972).
[8]S. Yoshida, S. Misawa, and S. Gonda, Appl. Phys. Lett.42,427(1983)
[9]H. Amano, I Akasaki, K. Hiramatsu, N. Koide, and N. Sawaki, Thin Solid Films 163,415(1988).
[10]H. Amano, M. Kito, K. Hiramatsu, and I. Akasaki, Jpn. J. Appl. Phys.28, L2112(1989).
[11]S. Nakamura, M.Senoh, and T. Mukai, Jpn. J. Appl. Phys.30, L1708(1990).
[12]S. Nakamura, M.Senoh, T. Mukai, and N. Iwasa, Jpn. J. Appl. Phys.31, L139(1992).
[13]S. Nakamura, S. Pearton, G. Fasol, The blue laser diode:the complete story, Berlin, Springer, (2000).
[14]S. Nakamura, M. Senoh, S. Nagahama, et al. Jpn. J. Appl. Phys.36, L1568(1997).
[15]M. A. Khan, J. N. Kuznia, D. T. Olson, et al. Appl. Phys. Lett.60,2917(1992).
[16]M. A. Khan, J. N. Kuznia, D. T. Olson, et al. Appl. Phys. Lett.63,2455(1993).
[17]X. Zhang, P. Kung, D. Walker, et al. Appl. Phys. Lett.67,2028(1995).
[18]S. J. Pearton, J. C. Zolper, R. J. Ibbetson, et al. J. Appl. Phys.86,1 (1999).
[19]V. Yu. Davydov, A. A. Klochikhin, R. P. Seisyanet, al. Phys. Stat. Sol. (b) 229, R1(2002).
[20]J.Wu, W. Walukiewicz, H. Lu, et al. Appl. Phys. Lett.80,4741(2002).
[21]A. G. Bhuiyan, A. Hashimoto, and A. Yamamoto, J. Appl. Phys.94, 2779(2003).
[22]T. L. Tansley, C. P. Foley, and T. Mukai, J. Appl. Phys.59,3241(1986).
[23]R. McClintock, A. Yasan, K. Mayes, et al. Appl. Phys. Lett.841248(2004).
[24]T. Suski, G. Franssen, P. Perlin, R. Bohdan, A. Bercha, P. Adamiec, F. Fybata, W. Trzeciakowshi, P. Prystawko, M. Leszczyski, I. Grzegory, and S. Porowski, Appl. Phys. Lett.84,1236(2004).
[25]M. Hansen, J. Piprek, P. M. Pattison, J. S. Spech, S. Nakamura, and S. P. Den Baars, Appl. Phys. Lett.81,4275(2002).
[26]T. D. Veal, P. H. Jefferson, L. F. J. Piper, C. F. McConville, T. B. Joyce, P. R. Chalker, L. Considine, H. Lu, and W. J. Schaff, Appl. Phys. Lett.89, 202110(2006).
[27]S. X. Li, K. M. Yu, J. Wu, R. E. Jones, W. Walukiewicz, J. W. Ager III, W. Shan, E. E. Haller, H, Lu, and W. J. Schaff, Phys. Rev. B 71,161201-1 (2005).
[28]T. L. Tansley, C. P. Foley, and T. Mukai, J. Appl. Phys.59,3241(1986).
[29]A. Yamamoto, Y. Murakami, K. Koide, et al. Phys. Stat. Sol. (b) 228,5(2001).
[30]H. Lu, W. J. Schaff, J. Hwang, H. Wu, G. Koley, and L. F. Eastman, Appl. Phys. Lett.79,1489(2001).
[31]Y. Saito, H. Harima, E. Kurimoto, et al. Phys. Stat. Sol. (b)234,801(2002).
[32]A. G. Bhuiyan, A. Hashimoto, and A. Yamamoto, J. Appl. Phys.94, 2779(2003).
[33]J. Wu, W. Walukiewicz, K. M. Yu, et al. J. Appl. Phys.94,6477(2003).
[34]Motoyichi Ohtsu, Progress in Nanophotonics, Springer, Berlin,2011
[1]Hamid Bentarzi, Transport in Metal-Oxide-Semiconductor Structures, Springer, New York,2011.
[2]Kwan chi kao, dielectric phenomena in solids,Elsevier Academic Press, California,2004.
[1]薛俊俊,南京大学硕士毕业论文
[2]朱正宇,胡巧声,半导体封装超声波压焊的工艺参数优化,电子工业专用设备,2006(134),55-60.
[1]S. K. Sahoo, D. Misra, D. C. Agrawal, Y. N. Mohapatra, S. B. Majumder, and R. S. Katiyar, J. Appl. Phys.108,074112 (2010).
[2]D. Nesheva, N. Nedev, Z. Levi, R. Bruggemann, E. Manolov, K. Kirilov, and S. Meier, Semicond. Sci. Technol.23,045015 (2008).
[3]A. J. Lowe, M. J. Powell, and S. R. Elliott, J. Appl. Phys.59,1251 (1986).
[1]Motoyichi Ohtsu, Progress in Nanophotonics, Springer, Berlin,2011
[2]Stefan A. Maier, Plasmonics fundamentals and applications, Springer, USA,2007
[3]Tolga Atay, Jung-Hoon, Arto V. Nurmikko, Strongly Interacting Plasmon Nanoparticle Pairs:From dipole-dipole Interaction to Conductively Coupled Regime, NANo LETTERS,2004,4,1624-1631.
[4]Jack J. Mock, et al, Distance-Dependent Plasmon Resonant Coupling between a Gold nanoparticle and Gold film,2008,8,2245-2252.
[2]S. D. Lester, F. A.Ponce, M. G. Craford, and D. A. Steigerwald, Appl Phys. Lett. 661249(1995)
[3]F. Fichter and Z. Anorg, Chem.54,322(1907).
[4]R. Juza, and H. Hahn, Zeitschrift fur anorganische und allgemeine Chemie, 239,282(1938).
[5]H. P. Maruska, and J. J. Tietjen, Appl. Phys. Lett.15,327(1969).
[6]J. I. Pankove, E. A. Miller, and J. E. Berkeyheiser, RCA review 32,383(1971).
[7]H. P. Maruska, W. C. Rhines, and D. A. Stevenson, Mater. Res. Bull.7, 777(1972).
[8]S. Yoshida, S. Misawa, and S. Gonda, Appl. Phys. Lett.42,427(1983)
[9]H. Amano, I Akasaki, K. Hiramatsu, N. Koide, and N. Sawaki, Thin Solid Films 163,415(1988).
[10]H. Amano, M. Kito, K. Hiramatsu, and I. Akasaki, Jpn. J. Appl. Phys.28, L2112(1989).
[11]S. Nakamura, M.Senoh, and T. Mukai, Jpn. J. Appl. Phys.30, L1708(1990).
[12]S. Nakamura, M.Senoh, T. Mukai, and N. Iwasa, Jpn. J. Appl. Phys.31, L139(1992).
[13]S. Nakamura, S. Pearton, G. Fasol, The blue laser diode:the complete story, Berlin, Springer, (2000).
[14]S. Nakamura, M. Senoh, S. Nagahama, et al. Jpn. J. Appl. Phys.36, L1568(1997).
[15]M. A. Khan, J. N. Kuznia, D. T. Olson, et al. Appl. Phys. Lett.60,2917(1992).
[16]M. A. Khan, J. N. Kuznia, D. T. Olson, et al. Appl. Phys. Lett.63,2455(1993).
[17]X. Zhang, P. Kung, D. Walker, et al. Appl. Phys. Lett.67,2028(1995).
[18]S. J. Pearton, J. C. Zolper, R. J. Ibbetson, et al. J. Appl. Phys.86,1 (1999).
[19]V. Yu. Davydov, A. A. Klochikhin, R. P. Seisyanet, al. Phys. Stat. Sol. (b) 229, R1(2002).
[20]J.Wu, W. Walukiewicz, H. Lu, et al. Appl. Phys. Lett.80,4741(2002).
[21]A. G. Bhuiyan, A. Hashimoto, and A. Yamamoto, J. Appl. Phys.94, 2779(2003).
[22]T. L. Tansley, C. P. Foley, and T. Mukai, J. Appl. Phys.59,3241(1986).
[23]R. McClintock, A. Yasan, K. Mayes, et al. Appl. Phys. Lett.841248(2004).
[24]T. Suski, G. Franssen, P. Perlin, R. Bohdan, A. Bercha, P. Adamiec, F. Fybata, W. Trzeciakowshi, P. Prystawko, M. Leszczyski, I. Grzegory, and S. Porowski, Appl. Phys. Lett.84,1236(2004).
[25]M. Hansen, J. Piprek, P. M. Pattison, J. S. Spech, S. Nakamura, and S. P. Den Baars, Appl. Phys. Lett.81,4275(2002).
[26]T. D. Veal, P. H. Jefferson, L. F. J. Piper, C. F. McConville, T. B. Joyce, P. R. Chalker, L. Considine, H. Lu, and W. J. Schaff, Appl. Phys. Lett.89, 202110(2006).
[27]S. X. Li, K. M. Yu, J. Wu, R. E. Jones, W. Walukiewicz, J. W. Ager III, W. Shan, E. E. Haller, H, Lu, and W. J. Schaff, Phys. Rev. B 71,161201-1 (2005).
[28]T. L. Tansley, C. P. Foley, and T. Mukai, J. Appl. Phys.59,3241(1986).
[29]A. Yamamoto, Y. Murakami, K. Koide, et al. Phys. Stat. Sol. (b) 228,5(2001).
[30]H. Lu, W. J. Schaff, J. Hwang, H. Wu, G. Koley, and L. F. Eastman, Appl. Phys. Lett.79,1489(2001).
[31]Y. Saito, H. Harima, E. Kurimoto, et al. Phys. Stat. Sol. (b)234,801(2002).
[32]A. G. Bhuiyan, A. Hashimoto, and A. Yamamoto, J. Appl. Phys.94, 2779(2003).
[33]J. Wu, W. Walukiewicz, K. M. Yu, et al. J. Appl. Phys.94,6477(2003).
[34]Motoyichi Ohtsu, Progress in Nanophotonics, Springer, Berlin,2011
[1]Hamid Bentarzi, Transport in Metal-Oxide-Semiconductor Structures, Springer, New York,2011.
[2]Kwan chi kao, dielectric phenomena in solids,Elsevier Academic Press, California,2004.
[1]薛俊俊,南京大学硕士毕业论文
[2]朱正宇,胡巧声,半导体封装超声波压焊的工艺参数优化,电子工业专用设备,2006(134),55-60.
[1]S. K. Sahoo, D. Misra, D. C. Agrawal, Y. N. Mohapatra, S. B. Majumder, and R. S. Katiyar, J. Appl. Phys.108,074112 (2010).
[2]D. Nesheva, N. Nedev, Z. Levi, R. Bruggemann, E. Manolov, K. Kirilov, and S. Meier, Semicond. Sci. Technol.23,045015 (2008).
[3]A. J. Lowe, M. J. Powell, and S. R. Elliott, J. Appl. Phys.59,1251 (1986).
[1]Motoyichi Ohtsu, Progress in Nanophotonics, Springer, Berlin,2011
[2]Stefan A. Maier, Plasmonics fundamentals and applications, Springer, USA,2007
[3]Tolga Atay, Jung-Hoon, Arto V. Nurmikko, Strongly Interacting Plasmon Nanoparticle Pairs:From dipole-dipole Interaction to Conductively Coupled Regime, NANo LETTERS,2004,4,1624-1631.
[4]Jack J. Mock, et al, Distance-Dependent Plasmon Resonant Coupling between a Gold nanoparticle and Gold film,2008,8,2245-2252.