高分辨X射线衍射表征氮化镓外延层缺陷密度
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摘要
利用高分辨X射线衍射方法,分析了在4H-Si C(0001)面上采用金属有机物化学气相沉积(MOCVD)生长的Ga N薄膜的位错。采用对称面衍射和斜对称面衍射等方法研究了晶面倾转角、面内扭转角、晶粒尺寸和晶面弯曲半径等参数,通过排除仪器、晶粒尺寸及晶面弯曲对摇摆曲线半高宽的影响,从而获得Ga N薄膜的螺位错密度和刃位错密度分别为4.62×107 cm-2和5.20×109 cm-2,总位错密度为5.25×109 cm-2。
The measurement of dislocation densities in heteroepitaxial semiconductor Ga N film is important for the developement of blue light-emitting diodes, laser diode and high temperature, high-frequency electronic devices. As there is no matching substrate material, Ga N thin films prepared by epitaxial growth often contain a large number of defects, most of which are edge dislocations. High resolution X-ray diffraction method and the mosaic model were used to measure and analyze the dislocation density of Ga N film fabricated by metal organic chemical vapor deposition(MOCVD) on a 4H-Si C substrate with an Al Ga N buffer layer. The crystal face tilting angle, in-plane twisting angle, grain size and crystal bending radius were investigated by symmetry and oblique symmetry diffraction methods. By eliminating the instrumental broadening width(mainly the incident beam divergence), grain size and wafer curvature influenced on the contribution to the full width at half maximum of rocking curves, Screw dislocation density and edge dislocation density of the Ga N film were accurately determined to be 4.62×107 cm-2 and 5.20×109 cm-2, respectively. The total dislocation density was 5.25×109 cm-2. There were less than 1% screw dislocations, and the ratio of mixed to edge dislocation failed to be determined.
The measurement of dislocation densities in heteroepitaxial semiconductor Ga N film is important for the developement of blue light-emitting diodes, laser diode and high temperature, high-frequency electronic devices. As there is no matching substrate material, Ga N thin films prepared by epitaxial growth often contain a large number of defects, most of which are edge dislocations. High resolution X-ray diffraction method and the mosaic model were used to measure and analyze the dislocation density of Ga N film fabricated by metal organic chemical vapor deposition(MOCVD) on a 4H-Si C substrate with an Al Ga N buffer layer. The crystal face tilting angle, in-plane twisting angle, grain size and crystal bending radius were investigated by symmetry and oblique symmetry diffraction methods. By eliminating the instrumental broadening width(mainly the incident beam divergence), grain size and wafer curvature influenced on the contribution to the full width at half maximum of rocking curves, Screw dislocation density and edge dislocation density of the Ga N film were accurately determined to be 4.62×107 cm-2 and 5.20×109 cm-2, respectively. The total dislocation density was 5.25×109 cm-2. There were less than 1% screw dislocations, and the ratio of mixed to edge dislocation failed to be determined.
引文
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[3]NI ZHI-FENG,YE ZHI-ZHEN.Influence of threading dislocations on physical properties of Ga N epilayers.Material Review,2003,17(11):9–12.
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[8]LU MIN,CHANG XIN,FANG HUI-ZHI.Etch-pits of Ga N films with different etching methods.Journal of Semiconductors,2004,25(11):1376–1380.
[9]LIU ZHAN-HUI,XIU XIANG-QIAN,ZHANG RONG,et al.Determination of Dislocation Density in HVPE-Ga N Layer by Two Different Methods.The 15th National Academic Conference on Compound Semiconductor,Microwave Device and Photoelectric Device.Guangzhou,2008:649–652.
[10]AYERS J E.The measurement of threading dislocation densities in semiconductor crystals by X-ray diffraction.Journal of Crystal Growth,1994,135:71–77.
[11]GAY P,HIRSCH P B,KELLY A.The estimation of dislocation densities in metals from X-ray data.Acta Metallurgica,1953,1:315–319.
[12]XU ZHEN-JIA.Semiconductor Analysis and Detection,The second edition.Beijing:Science Press,2012:88–89.
[13]METZGER T,HOPLERE R,BORN E,et al.Defect structure of epitaxial Ga N films determined by transmission electron microscopy and triple-axis X-ray diffractometry.Philosophical Magazine A,1998,77(4):1013–1025.
[14]MORAM M A,VICKERS M E.X-ray diffraction of III-nitrides.Reports on Progress in Physics,2009,72(036502):1–40.
[2]MORAN B,WU F,ROMANOV A E,et al.Structural and morphological evolution of Ga N grown by metalorganic chemical vapor deposition on Si C substrates using an Al N initial layer.Journal of Crystal Growth,2004,273(1/2):38–47.
[3]NI ZHI-FENG,YE ZHI-ZHEN.Influence of threading dislocations on physical properties of Ga N epilayers.Material Review,2003,17(11):9–12.
[4]CHERNS D,HENLEY S J,PONCE F A.Edge and screw dislocations as nonradiative centers in In Ga N/Ga N quantum well luminescence.Applied Physics Letters,2001,78(18):2961–2963.
[5]PARISH G,KELLER S,KOZODOY P,et al.High-performance(Al,Ga)N-based solar-blind ultraviolet p–i–n detectors on laterally epitaxially overgrown Ga N.Applied Physics Letters,1999,75(2):247–249.
[6]NAKAMURA S.In Ga N-based Laser Diodes with an Estimated Lifetime of Longer Than 10,000 Hours.Part of the SPIE Conference on Physics and Simulation of Qotoelectronic Devices VI,California,1998:2–13.
[7]DMITRI N Z,ZUZANNA L W.Structural TEM study of nonpolar a-plane gallium nitride grown on(1120)4H–Si C by organometallic vapor phase epitaxy.Physical Review B,2005,71(235334):1–9.
[8]LU MIN,CHANG XIN,FANG HUI-ZHI.Etch-pits of Ga N films with different etching methods.Journal of Semiconductors,2004,25(11):1376–1380.
[9]LIU ZHAN-HUI,XIU XIANG-QIAN,ZHANG RONG,et al.Determination of Dislocation Density in HVPE-Ga N Layer by Two Different Methods.The 15th National Academic Conference on Compound Semiconductor,Microwave Device and Photoelectric Device.Guangzhou,2008:649–652.
[10]AYERS J E.The measurement of threading dislocation densities in semiconductor crystals by X-ray diffraction.Journal of Crystal Growth,1994,135:71–77.
[11]GAY P,HIRSCH P B,KELLY A.The estimation of dislocation densities in metals from X-ray data.Acta Metallurgica,1953,1:315–319.
[12]XU ZHEN-JIA.Semiconductor Analysis and Detection,The second edition.Beijing:Science Press,2012:88–89.
[13]METZGER T,HOPLERE R,BORN E,et al.Defect structure of epitaxial Ga N films determined by transmission electron microscopy and triple-axis X-ray diffractometry.Philosophical Magazine A,1998,77(4):1013–1025.
[14]MORAM M A,VICKERS M E.X-ray diffraction of III-nitrides.Reports on Progress in Physics,2009,72(036502):1–40.