图形衬底上GaN材料的外延生长研究
摘要
本文利用MOCVD设备在几种不同形貌的图形衬底上进行了GaN材料的一系列外延生长实验,结合多种表征手段,研究了温度、压力、流量等生长参数对外延生长GaN材料的结晶质量、表面形貌等的影响,针对关键生长参数进行了优化实验,结合相关理论分析了图形衬底上外延生长的机理。
对于不同形貌的图形衬底,利用SEM进行了表面形貌的表征,对外延生长材料的结晶质量采用XRD进行表征分析,结合AFM的结果,分析外延层的表面粗糙度,通过分析外延材料的湿法腐蚀结果比较了图形衬底上不同位置的外延生长材料的缺陷密度。
1、对三角形腐蚀坑产生机理、化学腐蚀的时间对外延材料的结晶质量和表面粗糙度产生的影响进行了理论的分析,针对外延片的XRD、SEM、AFM等测试结果优化了腐蚀时间;
2、结合AFM结果分析了轰击台阶面的成因,在结晶质量的角度上优化了轰击时间,并结合微台阶理论对斜切结构对外延生长的影响进行了分析,最后优化了外延生长温度这一重要的生长参数;
3、采用柱状图形衬底外延生长GaN材料,通过与普通蓝宝石衬底上外延生长的比较,论述了图形衬底上外延生长材料的机理和特点,分析了Ⅴ/Ⅲ与生长速率的关系,依次优化了Ⅴ/Ⅲ、低温缓冲层的生长时间等对材料结晶质量的影响,最后,利用湿法化学腐蚀的方法对比了柱状区域和台面区域处的缺陷分布规律,定性地论述了在柱状图形衬底上外延生长材料的区域分化的特点。
Research of high quality GaN epitaxial layer grown on several different kinds of patterned sapphire substrates (PSSs) by MOCVD through a series of growing and testing experiments was developed. The influence of several growth parameters such as temperature、pressure and flux on crystal quality and morphology of epitaxial layer was also researched. Then some key process parameters were optimized and the mechanism of epitaxial growth on PSS was discussed combining with some related theories.
For these different kinds of PSSs, SEM was used to characterize the morphology and XRD was used to research the crystal quality ,the surface roughness and the size of dislocation pits were investigated by AFM, also the epitaxial material of different locations of the PSS were compared with the help of chemical etching method.
1、Theoretically analysis of the formative mechanism of triangle etching pits and the effect of chemical etching time on the crystal quality and surface roughness of epitaxial layer was processed, meanwhile, the etching time was optimized with the help of XRD、SEM and AFM;
2、Formative mechanism of step-surface was analyzed combinee with the results of AFM, etching time was optimized on bese of crystal quality, after explanation of the effect of declining structure on epitaxial layer, growth temperature, the key parameter in epitaxial growth, was optimized;
3、Growth mechanism and characteristic of GaN grown on pillar-shape PSS was discussed, the relationship betweenⅤ/Ⅲand growth rate was analyzed, following the optimization ofⅤ/Ⅲ、growth time of LT-uffer layer, regional difference existing in epitaxial layer on piller-shape PSS was qualitative analyzed with the help of chemical etching method.
对于不同形貌的图形衬底,利用SEM进行了表面形貌的表征,对外延生长材料的结晶质量采用XRD进行表征分析,结合AFM的结果,分析外延层的表面粗糙度,通过分析外延材料的湿法腐蚀结果比较了图形衬底上不同位置的外延生长材料的缺陷密度。
1、对三角形腐蚀坑产生机理、化学腐蚀的时间对外延材料的结晶质量和表面粗糙度产生的影响进行了理论的分析,针对外延片的XRD、SEM、AFM等测试结果优化了腐蚀时间;
2、结合AFM结果分析了轰击台阶面的成因,在结晶质量的角度上优化了轰击时间,并结合微台阶理论对斜切结构对外延生长的影响进行了分析,最后优化了外延生长温度这一重要的生长参数;
3、采用柱状图形衬底外延生长GaN材料,通过与普通蓝宝石衬底上外延生长的比较,论述了图形衬底上外延生长材料的机理和特点,分析了Ⅴ/Ⅲ与生长速率的关系,依次优化了Ⅴ/Ⅲ、低温缓冲层的生长时间等对材料结晶质量的影响,最后,利用湿法化学腐蚀的方法对比了柱状区域和台面区域处的缺陷分布规律,定性地论述了在柱状图形衬底上外延生长材料的区域分化的特点。
Research of high quality GaN epitaxial layer grown on several different kinds of patterned sapphire substrates (PSSs) by MOCVD through a series of growing and testing experiments was developed. The influence of several growth parameters such as temperature、pressure and flux on crystal quality and morphology of epitaxial layer was also researched. Then some key process parameters were optimized and the mechanism of epitaxial growth on PSS was discussed combining with some related theories.
For these different kinds of PSSs, SEM was used to characterize the morphology and XRD was used to research the crystal quality ,the surface roughness and the size of dislocation pits were investigated by AFM, also the epitaxial material of different locations of the PSS were compared with the help of chemical etching method.
1、Theoretically analysis of the formative mechanism of triangle etching pits and the effect of chemical etching time on the crystal quality and surface roughness of epitaxial layer was processed, meanwhile, the etching time was optimized with the help of XRD、SEM and AFM;
2、Formative mechanism of step-surface was analyzed combinee with the results of AFM, etching time was optimized on bese of crystal quality, after explanation of the effect of declining structure on epitaxial layer, growth temperature, the key parameter in epitaxial growth, was optimized;
3、Growth mechanism and characteristic of GaN grown on pillar-shape PSS was discussed, the relationship betweenⅤ/Ⅲand growth rate was analyzed, following the optimization ofⅤ/Ⅲ、growth time of LT-uffer layer, regional difference existing in epitaxial layer on piller-shape PSS was qualitative analyzed with the help of chemical etching method.
引文
[01] Pearton S J, Zopler J C, Shurl R J, et al. Processing, Defects, and Devices[J]. Journal of Applied Physics, 1999,86(1):1-78.
[02]段猛,郝跃. GaN基蓝色LED的研究进展[J],西安电子科技大学学报,2003,30(1):60-65.
[03]段猛碳化硅衬底上氮化镓薄膜材料及其发光器件特性研究[D],西安:西安电子科技大学,2003.
[04] Chen Q, Yang J W, Blasinggame M, et al. Microwave Electronics Device Applications of AlGaN/GaN Heterostructure[J]. Material Science and Engineering B, 1999, 59(2): 395-400.
[05] Shur M, Gelment B, Khan M A, Electron Mobility in Two-dimensional Electron Gas in AlGaN/GaN Heterostructres and in Bulk GaN[J]. Journal of Electronic Materials, 1996, 25(5): 777-785.
[06]陈元灯LED制造技术与应用[M],北京:电子出版社,2007.
[07] Wen Shangsheng. Study and development of high brightness blue GaN-based LED[J]. Chinese Journal of Quantum. 2003, 20(10).
[08] Fang Zhilie. Future applications of light emitting diodes[J]. Physics and Advanced Technology, 2003, 32(5): 295-301.
[09] Wang Erzhen, Wang Chunfeng. Development and application of white LED[J]. Electron-Optics Technology. 2002, 43(1):1-9.
[10] Li Zhonghui, Ding Xiaomin, Yang zhijian et al. Characteristics of high brightness InGaN-based white emitting diodes[J]. J.infrares Millim Waves, 2002, 21(5):390-392.
[11] Subramanian Muthu, Schuurmans F J, Pashley M D. Red, green, and blue LED based white light generation: Issues and control[C]. Industry Application Conferences, 2002. 37th IAS Annual Meeting, 2002, 13-18.
[12] Regina M M, Mueller G O, Krames M R, et al. High-power phosphor-converted light-emitting diodes[J]. IEEE Photon. Technol. Lett. 2002, 14(4):450-452.
[13] Chen C H, Chang S J, Su Y K, et al. Hitride-based cascade near white light-emitting diodes[J]. IEEE Photon Technology Letter. 2002, 14(7):908-910.
[14]顾忠良,GaN半导体研究与进展[J],半导体情报,1999,36(4):10-14.
[15]许敏,袁凤坡,陈国鹰等,调制掺杂对AlGaN/GaN HEMT材料电学性能的影响[J].工艺技术与材料, 2007, 32(30):230-233.
[16] J.M.Redwing, M.A.Tischler, and J.S.Flynn, Two-dimensional electron gas properties of AlGaN/GaN heterostructures grown on 6H-SiC and sapphire substrates[J]. Appl.Phys.Lett, 1996, 69(7):963-965.
[17]罗超帆,超高亮度InGaN蓝、白光LED之碳化硅与蓝宝石衬底材料的探讨。第八届全国LED产业研讨与学术会议论文集.
[18] Wang J. Research of GaN lateral overgrown on sapphire PSS[D]. Institute of Condensed Matter Physics, Chinese Academy of Sciences. 2006,05,01.
[19] Y. Kato, S. Kitamura, K. Hiramatsu, et al. Journal of Crystal Growth, 1994,144:133.
[20]杨树人,丁墨元,外延生长技术[M].北京:国防工业出版社,1992.
[21] R. Dwilinski, R. Doradziski, J. Garczy ski, L. Sierzputowski, J. M. Baranowski, M. Kamiska, Mater. Science. Eng. B50, 46 (1997).
[22] Liang C. G, Zhang J. GaN-Dawn of 3rd-Generation-Semiconductors. Chinese Journal of Semiconductors. 1999, Feburary, v20, n2: 89-90.
[23] D. J. Wallis, A. M. Keir, R. S. Balmer, et al. Composition measurement in strained AlGaN epitaxy layers using X-ray diffraction[J]. Applied Physics Letters, 2004, 85(26): 6359-6361.
[24] H. Heinke, V. Kirchner, S. Einfeldt, et al, X-ray diffraction analysis of the defect structure in epitaxial GaN[J]. Applied Physics Letters, 2000, 77(14): 2145-2147.
[25] S. R. Lee, A. M. West, A. A. Allerman, et al, Effect of Threading Dislocation on the Bragg Peak widths of GaN, AlGaN, and AlN heterolayers[J]. Applied Physics Letters, 2005, 86(24): 241904.
[26] Shigeaki Sumiya, Youhua Zhu, Jicai Zhang, et al, AlGaN-Based deep Ultraviolet Light-Emitting Diodes Grown on Epitaxial AlN/Sapphire Templates[J]. JapaneseJournal of Applied Physics, 2008, 47(1): 43-46.
[27] W. K. Wang, D. S. Wuu, S. H. Lin, et al, Growth and characterization of InGaN-based light-emitting diodes on patterned sapphire substrates[J]. Journal of Physics and Chemistry of Solids, 69(2008): 714-718.
[28]彭冬生,冯玉春,王文欣等,蓝宝石表面处理对氮化镓薄膜的影响[J]。光子学报,Vol. 36 NO. 8 (2007)。
[29] Zhang W, Hao Q, Liu C C, No mask epitaxial lateral overgrowth of GaN on sapphire [J]. Journal of Alloys and Compounds, 2007, 456(1-2):368~371.
[30] Grudowski P A, Holmes A L, Eiting C, et al. Applied Physics Letter[J]. 1996, 69: 3626-3828.
[31] Lin J C, Su Y K, Chang S J, et al. Journal of Crystal Growth[J]. 2005, 285: 481-485.
[32] Shen X Q, Matsuhata, Okumura, H, [J]. Applied Physics Letter, 2005, 86: 021912-101915.
[33] Figge S, Enfeldt S, Hommel M, et al, In situ and ex-situ evaluation of the film coalescence for GaN growth on GaN nucleation layers[J]. Journal of Crystal growth, 2000, 221: 262-266.
[34] Speck J S, Keller S, Wu X H, et al, Dislocation generation in GaN heteroepitaxy[J]. Journal of Crystal growth, 1998, 189/190: 231-243.
[35]李述体,范广涵,周天明等,生长模式控制对MOCVD生长GaN性能的影响[J]。华南师范大学学报(自然科学版),2005,4:58-62。
[36]江洋,罗毅,薛小林等,基于图形衬底生长的GaN位错机制分析[J]。光电子/激光学报,Vol. 19 NO. 4 (2008)。
[37]彭冬生,冯玉春等,预处理蓝宝石衬底上生长高质量GaN显示薄膜[J]。电子器件,Vol. 31 NO. 1 (2008)。
[38]金瑞琴,赵德刚,刘建平等,GaN生长速率的研究[J]。半导体学报,Vol. 26 NO. 4 (2005)。
[39] Yang T, Uchida K, Mishima T, et al, Control of initial nucleation by reducing theⅤ/Ⅲratio during the early stages of GaN growth. Physics Status Solid A, 2000,180:45.
[40] Wang T, Shimahama T, Sun H B, Wang H X, et al, Influence of buffer layer and growth temperature on the properties of an un-doped GaN on sapphire substrate by MOCVD[J]. Applied Physics Letter, 2000, 76:2200.
[41]高志远,郝跃,张进城等,KOH热腐蚀法准确估算GaN的位错密度[J]。功能材料与器件学报,Vol. 14 NO. 4 (2008)。
[42] Hull D, Bacon D I. Introduction to dislocations[M]. Beijing science, 1990.
[43] Friedel I, Dislocations [M]. Beijing science, 1980.
[44] De keijiser Th H, Mittemeijier E J, Rozemdaal H C E, The determination of crystallite size and lattice strain parameters in conjunction with the profile refinement method for the determination of crystal structures[J], Journal of Applied Crystal, 1983, 16: 309-316.
[02]段猛,郝跃. GaN基蓝色LED的研究进展[J],西安电子科技大学学报,2003,30(1):60-65.
[03]段猛碳化硅衬底上氮化镓薄膜材料及其发光器件特性研究[D],西安:西安电子科技大学,2003.
[04] Chen Q, Yang J W, Blasinggame M, et al. Microwave Electronics Device Applications of AlGaN/GaN Heterostructure[J]. Material Science and Engineering B, 1999, 59(2): 395-400.
[05] Shur M, Gelment B, Khan M A, Electron Mobility in Two-dimensional Electron Gas in AlGaN/GaN Heterostructres and in Bulk GaN[J]. Journal of Electronic Materials, 1996, 25(5): 777-785.
[06]陈元灯LED制造技术与应用[M],北京:电子出版社,2007.
[07] Wen Shangsheng. Study and development of high brightness blue GaN-based LED[J]. Chinese Journal of Quantum. 2003, 20(10).
[08] Fang Zhilie. Future applications of light emitting diodes[J]. Physics and Advanced Technology, 2003, 32(5): 295-301.
[09] Wang Erzhen, Wang Chunfeng. Development and application of white LED[J]. Electron-Optics Technology. 2002, 43(1):1-9.
[10] Li Zhonghui, Ding Xiaomin, Yang zhijian et al. Characteristics of high brightness InGaN-based white emitting diodes[J]. J.infrares Millim Waves, 2002, 21(5):390-392.
[11] Subramanian Muthu, Schuurmans F J, Pashley M D. Red, green, and blue LED based white light generation: Issues and control[C]. Industry Application Conferences, 2002. 37th IAS Annual Meeting, 2002, 13-18.
[12] Regina M M, Mueller G O, Krames M R, et al. High-power phosphor-converted light-emitting diodes[J]. IEEE Photon. Technol. Lett. 2002, 14(4):450-452.
[13] Chen C H, Chang S J, Su Y K, et al. Hitride-based cascade near white light-emitting diodes[J]. IEEE Photon Technology Letter. 2002, 14(7):908-910.
[14]顾忠良,GaN半导体研究与进展[J],半导体情报,1999,36(4):10-14.
[15]许敏,袁凤坡,陈国鹰等,调制掺杂对AlGaN/GaN HEMT材料电学性能的影响[J].工艺技术与材料, 2007, 32(30):230-233.
[16] J.M.Redwing, M.A.Tischler, and J.S.Flynn, Two-dimensional electron gas properties of AlGaN/GaN heterostructures grown on 6H-SiC and sapphire substrates[J]. Appl.Phys.Lett, 1996, 69(7):963-965.
[17]罗超帆,超高亮度InGaN蓝、白光LED之碳化硅与蓝宝石衬底材料的探讨。第八届全国LED产业研讨与学术会议论文集.
[18] Wang J. Research of GaN lateral overgrown on sapphire PSS[D]. Institute of Condensed Matter Physics, Chinese Academy of Sciences. 2006,05,01.
[19] Y. Kato, S. Kitamura, K. Hiramatsu, et al. Journal of Crystal Growth, 1994,144:133.
[20]杨树人,丁墨元,外延生长技术[M].北京:国防工业出版社,1992.
[21] R. Dwilinski, R. Doradziski, J. Garczy ski, L. Sierzputowski, J. M. Baranowski, M. Kamiska, Mater. Science. Eng. B50, 46 (1997).
[22] Liang C. G, Zhang J. GaN-Dawn of 3rd-Generation-Semiconductors. Chinese Journal of Semiconductors. 1999, Feburary, v20, n2: 89-90.
[23] D. J. Wallis, A. M. Keir, R. S. Balmer, et al. Composition measurement in strained AlGaN epitaxy layers using X-ray diffraction[J]. Applied Physics Letters, 2004, 85(26): 6359-6361.
[24] H. Heinke, V. Kirchner, S. Einfeldt, et al, X-ray diffraction analysis of the defect structure in epitaxial GaN[J]. Applied Physics Letters, 2000, 77(14): 2145-2147.
[25] S. R. Lee, A. M. West, A. A. Allerman, et al, Effect of Threading Dislocation on the Bragg Peak widths of GaN, AlGaN, and AlN heterolayers[J]. Applied Physics Letters, 2005, 86(24): 241904.
[26] Shigeaki Sumiya, Youhua Zhu, Jicai Zhang, et al, AlGaN-Based deep Ultraviolet Light-Emitting Diodes Grown on Epitaxial AlN/Sapphire Templates[J]. JapaneseJournal of Applied Physics, 2008, 47(1): 43-46.
[27] W. K. Wang, D. S. Wuu, S. H. Lin, et al, Growth and characterization of InGaN-based light-emitting diodes on patterned sapphire substrates[J]. Journal of Physics and Chemistry of Solids, 69(2008): 714-718.
[28]彭冬生,冯玉春,王文欣等,蓝宝石表面处理对氮化镓薄膜的影响[J]。光子学报,Vol. 36 NO. 8 (2007)。
[29] Zhang W, Hao Q, Liu C C, No mask epitaxial lateral overgrowth of GaN on sapphire [J]. Journal of Alloys and Compounds, 2007, 456(1-2):368~371.
[30] Grudowski P A, Holmes A L, Eiting C, et al. Applied Physics Letter[J]. 1996, 69: 3626-3828.
[31] Lin J C, Su Y K, Chang S J, et al. Journal of Crystal Growth[J]. 2005, 285: 481-485.
[32] Shen X Q, Matsuhata, Okumura, H, [J]. Applied Physics Letter, 2005, 86: 021912-101915.
[33] Figge S, Enfeldt S, Hommel M, et al, In situ and ex-situ evaluation of the film coalescence for GaN growth on GaN nucleation layers[J]. Journal of Crystal growth, 2000, 221: 262-266.
[34] Speck J S, Keller S, Wu X H, et al, Dislocation generation in GaN heteroepitaxy[J]. Journal of Crystal growth, 1998, 189/190: 231-243.
[35]李述体,范广涵,周天明等,生长模式控制对MOCVD生长GaN性能的影响[J]。华南师范大学学报(自然科学版),2005,4:58-62。
[36]江洋,罗毅,薛小林等,基于图形衬底生长的GaN位错机制分析[J]。光电子/激光学报,Vol. 19 NO. 4 (2008)。
[37]彭冬生,冯玉春等,预处理蓝宝石衬底上生长高质量GaN显示薄膜[J]。电子器件,Vol. 31 NO. 1 (2008)。
[38]金瑞琴,赵德刚,刘建平等,GaN生长速率的研究[J]。半导体学报,Vol. 26 NO. 4 (2005)。
[39] Yang T, Uchida K, Mishima T, et al, Control of initial nucleation by reducing theⅤ/Ⅲratio during the early stages of GaN growth. Physics Status Solid A, 2000,180:45.
[40] Wang T, Shimahama T, Sun H B, Wang H X, et al, Influence of buffer layer and growth temperature on the properties of an un-doped GaN on sapphire substrate by MOCVD[J]. Applied Physics Letter, 2000, 76:2200.
[41]高志远,郝跃,张进城等,KOH热腐蚀法准确估算GaN的位错密度[J]。功能材料与器件学报,Vol. 14 NO. 4 (2008)。
[42] Hull D, Bacon D I. Introduction to dislocations[M]. Beijing science, 1990.
[43] Friedel I, Dislocations [M]. Beijing science, 1980.
[44] De keijiser Th H, Mittemeijier E J, Rozemdaal H C E, The determination of crystallite size and lattice strain parameters in conjunction with the profile refinement method for the determination of crystal structures[J], Journal of Applied Crystal, 1983, 16: 309-316.