Structural, Morphological, Optical and Electrical Properties of Zn_(1-x)Cd_xO Solid Solution Grown on a- and r-Plane Sapphire Substrate by MOCV

Afif Fouzri, Mohamed Amine Boukadhaba, Al Housseynou Tauré, Nawfel Sakly, Amor Bchetnia, Vincent Sallet

Group Study of Condensed Matter, CNRS/University of Versailles Saint Quentin en Yvelines, Paris, France.
Laboratory of Physical Chemistry Interfaces, Department of Physics, Faculty of Sciences of Monastir, University of Monastir, Monastir, Tunisia.
Laboratory of Physical Chemistry Materials, USCR “High Resolution X-Ray Diffractometer”, Department of Physics, Faculty of Sciences of Monastir, University of Monastir, Monastir, Tunisia.
Research Unit of Heteroepitaxy and Its Applications, Department of Physics, Faculty of Sciences of Monastir, University of Monastir, Monastir, Tunisia.

DOI: 10.4236/jcpt.2013.31006                

Abstract

Zn_(1-x)Cd_xO films have been grown on (a-plane) and (r-plane) sapphire substrate by metal organic chemical vapor deposition. A maximum cadmium incorporation of 8.5% and 11.2% has been respectively determined for films deposited on a- and r-plane sapphire. The optical transmission spectra and energy band-gap equation established by Makino et al. were used to estimate the cadmium mole fraction of the solid solutions. Structural, morphological and optical properties of these films were examined using high resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM) and room and low temperature photoluminescence (Pl) as Cd incorporation and employed substrate. X-ray diffraction study revealed that all films had wurtzite phase but solid solution grown on a-plane sapphire are polycrystalline with a preferred orientation along the [0001] direction and a-plane film are epitaxially grown on r-plane sapphire. AFM image show significant differences between morphologies depending on orientation sapphire substrate but no significant differences on surface roughness have been found. The near band-edge photoluminescence emission shifts gradually to lower energies as Cd is incorporated and reaches 2.916 eV for the highest Cd content (11.2%) at low temperature (20 K). The room temperature hall mobility decreases with the Cd incorporation but it is larger for Zn_(1-x)Cd_xO grown on r-plane sapphire.

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	H. Ohta, K. Kawamura, M. Orita and M. Hirano, “Current Injection Emission from a Transparent p-n Junction Composed of p-SrCu2O2/n-ZnO,” Applied Physics Letters, Vol. 77, No. 4, 2000, p. 475-477. doi:10.1063/1.127015
[2]	T. Aoki, Y. Hatawaka and D. C. Look, “ZnO Diode Fabricated by Excimer-Laser Doping,” Applied Physics Letters, Vol. 76, No. 22, 2000, pp. 3257-3258. doi:10.1063/1.126599
[3]	A. Ohtomo, M. Kawasaki, T. Koida, K. Masubuchi and H. Koinuma, “MgxZn1?xO as a II-VI Widegap Semiconductor Alloy,” Applied Physics Letters, Vol. 72, No. 19, 1998, pp. 2466-2468. doi:10.1063/1.121384
[4]	A. Ohtomo, R. Shiroki, I. Ohkubo, H. Koinuma and M. Kawasaki, “Thermal Stability of Supersaturated MgxZn1?xO Alloy Films and MgxZn1?xO/ZnO Heterointerfaces,” Applied Physics Letters, Vol. 75, No. 26, 1999, pp. 4088-4090. doi:10.1063/1.125545
[5]	T. Makino, C. H. Chia, N. T. Tuan, Y. Segawa, M. Kawasaki, A. Ohtomo, K. Tamura and H. Koinuma, “Radiative and Nonradiative Recombination Processes in Lattice-Matched (Cd,Zn)O/(Mg,Zn)O Multiquatum Wells,” Applied Physics Letters, Vol. 77, No. 11, 2000, pp. 1632-1635. doi:10.1063/1.1308540
[6]	T. Makino, Y. Segawa, M. Kawasaki, A. Ohtomo, R. Shiroki, K. Tamura, T. Yasuda and H. Koinuma, “Band Gap Engineering Based on MgxZn1?xO and CdyZn1?yO Ternary Alloy Films,” Applied Physics Letters, Vol. 78, No. 9, 2001, pp. 1237-1239. doi:10.1063/1.1350632
[7]	A. Nakamura, J. Ishihara, S. Shigemori, K. Yamamoto, T. Aoki, H. Gotoh and J. Temmyo, “Characterization of Wurtzite Zn1?xCdxO Films Using Remote Plasma-Enhanced Metalorganic Chemical Vapor Deposition,” Japanese Journal of Applied Physics, Vol. 43, 2004, pp. L1452-L1454. doi:10.1143/JJAP.43.L1452
[8]	B. Gil, P. Lefebvre, T. Bretagnon, T. Guillet, J. A. Sans, T. Taliercio, and C. Morhain, “Spin-Exchange Interaction in ZnO-Based Quantum Wells, ” Physical Review B, Vol. 74, No. 15, 2006, Article ID: 153302. doi:10.1103/PhysRevB.74.153302
[9]	P. Waltereit, O. Brandt, A. Trampert, H. T. Grahn, J. Menniger, M. Ramsteiner, M. Reiche, and K. H. Ploog, “Nitride Semiconductors Free of Electrostatic Fields for Efficient White Light-Emitting Diodes,” Nature, Vol. 406, 2000, pp. 865-867. doi:10.1038/35022529
[10]	C. R. Gorla, N. W. Emanetoglu, S. Liang, W. E. Mayo, Y. Lu, M. Wraback, and H. Shen, “Structural, Optical, and Surface Acoustic Wave Properties of Epitaxial ZnO Films Grown on Sapphire by Metalorganic Chemical Vapor Deposition,” Journal of Applied Physics, Vol. 85, No. 5, 1999, pp. 2595-2602. doi:10.1063/1.369577
[11]	J. M. Chauveau, M. Laügt, P. Vennegues, M. Teisseire, B. Lo, C. Deparis, C. Morhain, and B. Vinter, “Non-Polar a-Plane ZnMgO/ZnO Quantum Wells Grown by Molecular Beam Epitaxy,” Semiconductor Science and Technology, Vol. 23, No. 3, 2008, Article ID: 035005. doi:10.1088/0268-1242/23/3/035005
[12]	J. Z??iga-Pérez, V. Mu?oz-Sanjosé, M. Loreng, G. Benndorf, S. Heitsch, D. Spemann and M. Grundmann, “Facets Evolution and Surface Electrical Properties of Nonpolar m-Plane ZnO Thin Films,” Journal of Applied Physics, Vol. 99, No. 2, 2006, Article ID: 023514. doi:10.1063/1.2163014
[13]	J. Tauc, R. Grigorvici and Y. Yanca, “Optical Properties and Electronic Structure of Amorphous Germanium,” Physica Status Solidi, Vol. 15, No. 2, 1966, pp. 627-637. doi:10.1002/pssb.19660150224
[14]	A. Fouzri, V. Sallet and M. Oumezzine, “A Comparative Structure and Morphology Study of Zn(1?x)CdxO Solid Solution Grown on ZnO and Different Sapphire Orientations,” Journal of Crystal Growth, Vol. 331, No. 1, 2011, pp. 18-24. doi:10.1016/j.jcrysgro.2011.06.056
[15]	S. Liang, H. Sheng, Y. Liu, Z. Huo, Y. Lu and H. Shen, “ZnO Schottky Ultraviolet Photodetectors,” Journal of Crystal Growth, Vol. 225, No. 2-4, 2001, pp. 110-113. doi:10.1016/S0022-0248(01)00830-2
[16]	J. M. Chauveau, P. Vennéguès, M. Laügt, C. Deparis, J. Z??iga-Pérez, and C. Morhain, “Interface Structure and Anisotropic Strain Relaxation of Nonpolar Wurtzite (11-20) and (10-10) Orientations: ZnO Epilayers Grown on Sapphire,” Journal of Applied Physics, Vol. 104, No. 7, 2008, Article ID: 073535. doi:10.1063/1.2996248
[17]	G. Saraf, Y. Lu and T. Siegrist, “In-Plane Anisotropic Strain in a-ZnO Films Grown on r-Sapphire Substrates,” Applied Physics Letters, Vol. 93, No. 4, 2008, Article ID: 041903. doi:10.1063/1.2965801
[18]	C. C. Kuo, W.-R. Liu, W. F. Hsieh, C.-H. Hsu, H. C. Hsu and L. C. Chen, “Crystal Symmetry Breaking of Wurtzite to Orthorhombic in Nonpolar a-ZnO Epifilms,” Applied Physics Letters, Vol. 95, No. 1, 2009, Article ID: 011905. doi:10.1063/1.3159470
[19]	F. Vigué, P. Vennéguès, C. Deparis, S. Vézian, M. Laügt and J. P. Faurié, “Growth Modes and Microstructures of ZnO Layers Deposited by Plasma-Assisted Molecular-Beam Epitaxy on (0001) Sapphire,” Journal of Applied Physics, Vol. 90, No. 10, 2001, pp. 5115-5119. doi:10.1063/1.1412572
[20]	S.W. Jung, S.J. An, G. Yi, C.U. Jung, S. Lee and S. Cho, “Ferromagnetic Properties of Zn1?xMnxO Epitaxial Thin Films,” Applied Physics Letters, Vol. 80, No. 24, 2002, pp. 4561-4563. doi:10.1063/1.1487927
[21]	C. Liu, F. Yun, B. Xiao, S. J. Cho, Y. T. Moon, H. Morkoc, M. Abouzaid, R. Ruterana, K. M. Yu and W. Walukiewicz, “Structural Analysis of Ferromagnetic Mn-Doped ZnO Thin Films Deposited by Radio Frequency Magnetron Sputtering,” Journal of Applied Physics, Vol. 97, No. 12, 2005, Article ID: 126107. doi:10.1063/1.1941465
[22]	A. Fouzri, M. A. Boukadhaba, V. Sallet and M. Oumezzine, “Structural Properties and Morphology of Zn(1?x)CdxO Solid Solution Grown on ZnO and c-Plane Sapphire,” Thin Solid Films, Vol. 520, No. 7, 2012, pp. 2582-2588. doi:10.1016/j.tsf.2011.11.027
[23]	J. J. Zhu, T. Aaltonen, V. Venkatachalapathy, A. Galeckas and A. Yu. Kuznetsov, “Structural and Optical Properties of Polar and Non-Polar ZnO Films Grown by MOVPE,” Journal of Crystal Growth, Vol. 310, No. 23, 2008, pp. 5020-5024. doi:10.1016/j.jcrysgro.2008.07.117
[24]	C. R. Gorla, W. E. Mayo, S. Liang and Y. Lu, “Structure and Interface-Controlled Growth Kinetics of ZnAl2O4 Formed at the (110) ZnO/(012) Al2O3 Interface,” Journal of Applied Physics, Vol. 87, No. 8, 2000, pp. 3736-3743. doi:10.1063/1.372454
[25]	S. K. Han, S. K. Hong, J. W. Lee, J. Y. Lee, H.-D. Yun, S.-W. Nam, S.-W. Chang, T. Minegishi and T. Yao, “Structural and Optical Properties of Non-Polar a-Plane ZnO Films Grown on r-Plane Sapphire Substrates by Plasma-Assisted Molecular-Beam Epitaxy,” Journal of Crystal Growth, Vol. 309, No. 2, 2007, pp. 121-127. doi:10.1016/j.jcrysgro.2007.09.025
[26]	F. Li, Y. Ding, P. Gao, X. Xin and Z. L. Wang, “Single-Crystal Hexagonal Disks and Rongs of ZnO: Low-Temperature, Large-Scale Synthesis and Growth Mechanism,” Angewandte Chemie International Edition, Vol. 43, No. 39, 2004, pp. 5238-5242. doi:10.1002/anie.200460783
[27]	Y. Peng, A-W. Xu, B. Deng, M. Antonietti and H. C?tfen, “Polymer-Controlled Crystallization of Zinc Oxide Hexagonal Nanorings and Disks,” The Journal of Physical Chemistry B, Vol. 110, No. 7, 2006, pp. 2988-2993. doi:10.1021/jp056246d
[28]	L. Wang, Y. Yu, W. Fang, J. Dai, Y. Chen, C. Mo and F. Jiang, “High-Quality ZnO Films Grown by Atmospheric Pressure Metal—Organic Chemical Vapor Deposition,” Journal of Crystal Growth, Vol. 283, No. 1-2, 2005, pp. 87-92. doi:10.1016/j.jcrysgro.2005.05.040
[29]	S. W. Jun, W. I. Park, H. D. Cheong, G. C. Yi and H. M. Jang, “Time-Resolved and Time-Integrated Photoluminescence in ZnO Epilayers Grown on Al2O3(0001) by Metalorganic Vapor Phase Epitaxy,” Applied Physics Letters, Vol. 80, No. 11, 2002, pp. 1924-1926. doi:10.1063/1.1461051
[30]	B. K. Meyer, H. Alves, D. M. Hofmann, W. Kriegseis, D. Forster, F. Bertram, J. Christen, A. Hoffmann, M. Strassburg, M. Dworzak, U. Haboeck and A. V. Rodina, “Bound exciton and Donor-Acceptor Pair Recombinations in ZnO,” Physica Status Solidi (B), Vol. 241, No. 2, 2004, pp. 231-260. doi:10.1002/pssb.200301962
[31]	ü. ?zgür, Ya. I. Alivov, C. Liu, A. Teke, M. A. Reshchikov, S. Do?an, V. Avrutin, S.-J. Cho and H. Morko?, “A Comprehensive Review of ZnO Materials and Devices,” Journal of Applied Physics, Vol. 98, No. 4, 2005, Article ID: 041301. doi:10.1063/1.1992666
[32]	M. Schirra, R. Schneider, A. Reiser, G. M. Prinz, M. Feneberg, J. Biskupek, U. Kaiser, C. E. Krill, K. Thonke and R. Sauer, “Stacking Fault Related 3.31-eV Luminescence at 130-meV Acceptors in Zinc Oxide,” Physical Review B, Vol. 77, No. 12, 2008, Article ID: 125215. doi:10.1103/PhysRevB.77.125215
[33]	K. Yamamoto, T. Tsuboi, T. Ohashi, T. Tawara, H. Gotoh, A. Nakamura and J. Temmyo, “Strcutural and Optical Properties of Zn(Mg,Cd)O Alloy Films Grown by Remote-Plasma-Enhanced MOCVD,” Journal of Crystal Growth, Vol. 312, No. 10, 2010, pp. 1703-1708. doi:10.1016/j.jcrysgro.2010.02.029
[34]	C. Sartel, N. Haneche, C. Vilar, G. Amiri, J.-M. Laroche, F. Jomard, A. Lusson, P. Galtier, V. Sallet, C. Couteau, J. Lin, R. Aad and G. Lérondel, “Growth Studies and Optical Properties of Zn1?xCdxO Films Grown by Metal-Organic Chemical-Vapor Deposition,” Journal of Vacuum Science & Technology A, Vol. 29, No. 3, 2011, Article ID: 03A114. doi:10.1116/1.3567960
[35]	A. Lusson, R. Legros, Y. Marfaing, and H. Mariette, “Alloy-Induced Broadening of Extrinsic and Intrinsic Exciton Luminescence in CdxHg1?xTe,” Solid State Communications, Vol. 67, No. 9, 1988, pp. 851-854. doi:10.1016/0038-1098(88)90116-0
[36]	P. Ding, X. Pan, J. Huang, B. Lu, H. Zhang, W. Chen and Z. Ye, “Growth of p-Type a-Plane ZnO Thin Films on r-Plane Sapphire Substrates by Plasma-Assisted Molecular Beam Epitaxy,” Materials Letters, Vol. 71, 2012, pp. 18-20. doi:10.1016/j.matlet.2011.12.030
[37]	P. Fons, K. Iwata, A. Yamada, K. Matsubara, S. Niki, K. Nakahara, T. Tanabe and H. Takasu, “Nucleation and Growth of ZnO on Sapphire Substrates Using Molecular Beam Epitaxy,” Journal of Crystal Growth, Vol. 227-228, 2001, pp. 911-916. doi:10.1016/S0022-0248(01)00927-7
[38]	D. C. Look, J. W. Hemsky and J. R. Stzelove, “Production and Annealing of Electron Irradiation Damage in ZnO,” Physical Review Letters, Vol. 82, No. 12, 1999, pp. 2552-2555. doi:10.1103/PhysRevLett.82.2552
[39]	S. P. Wang, C. X. Shan, B. Yao, B. H. Li, J. Y. Zhang, D. X. Zhao, D. Z. Shen and X. W. Fan, “Electrical and Optical Properties of ZnO Films Grown by Molecular Beam Epitaxy,” Applied Surface Science, Vol. 255, No. 9, 2009, pp. 4913-4915. doi:10.1016/j.apsusc.2008.12.035
[40]	A. Y. Polyakov, N. B. Smirnov, A. I. Belogorokhov, A. V. Govorkov, E. A. Kozhukhova, A. V. Osinsky, J. Q. Xie, B. Hertog and S. J. Pearton, “Electrical Properties and Deep Traps in ZnO Films Grown by Molecular Beam Epitaxy,” Journal of Vacuum Science & Technology B, Vol. 25, No. 6, 2007, pp. 1794-1798. doi:10.1116/1.2790918
[41]	Y. S. Jung, O. V. Kononenko and W, K. Choi, “Electron Transport in High Quality Undoped ZnO Film Grown by Plasma-Assisted Molecular Beam Epitaxy,” Solid State Communications, Vol. 137, No. 9, 2006, pp. 474-477. doi:10.1016/j.ssc.2005.12.038
[42]	K. Miyamoto, M. Sano, H. Kato and T. Yao, “High-Electron-Mobility ZnO Epilayers Grown by Plasma-Assisted Molecular Beam Epitaxy,” Journal of Crystal Growth, Vol. 265, No. 1-2, 2004, pp. 34-40. doi:10.1016/j.jcrysgro.2004.01.035
[43]	S. Chu, M. Morshed, L. Li, J. Huang and J. Liu, “Smooth Surface, Low Electron Concentration, and High Mobility ZnO Films on c-Plane Sapphire,” Journal of Crystal Growth, Vol. 325, No. 1, 2011, pp. 36-40. doi:10.1016/j.jcrysgro.2011.04.036
[44]	B. J. Zheng, J. S. Lian, L. Zhao and Q. Jiang, “Structural, Optical and Electrical Properties of Zn1?xCdxO Thin Films Prepared by PLD,” Applied Surface Science, Vol. 257, No. 13, 2011, pp. 5657-5662. doi:10.1016/j.apsusc.2011.01.070
[45]	P. Vennegues, J. M. Chauveau, M. Korytov, C. Deparis, J. Z??iga-Pérez and C. Morhain, “Interfacial Structure and Defect Analysis of Nonpolar ZnO Films Grown on r-Plane Sapphire by Molecular Beam Epitaxy,” Journal of Applied Physics, Vol. 103, No. 8, 2008, Article ID: 083525. doi:10.1063/1.2905220
[46]	H. S. Kang, S. W. Kim, J. H. Kim, S. Y. Lee, Y. Li, J. Sik Lee, J. K. Lee, M. A. Nastasi, S. A. Crooker and Q. X. Jia, “Optical Property and Stokes’ Shift of Zn1?xCdxO Thin Films Depending on Cd Content,” Journal of Applied Physics, Vol. 99, No. 6, 2006, Article ID: 066113. doi:10.1063/1.2186372