J. Semicond. > 2013, Volume 34 > Issue 12 > 122003, doi: 10.1088/1674-4926/34/12/122003
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SEMICONDUCTOR PHYSICS

Giant in-plane optical anisotropy of a-plane ZnO on r-plane sapphire

Shujie Wu, Yonghai Chen, Xudong Qin, Hansong Gao, Jinling Yu, Laipan Zhu, Yuan Li and Kai Shi

+ Author Affiliations

 Corresponding author: Wu Shujie, wusj@semi.ac.cn; Chen Yonghai, yhchen@semi.ac.cn

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Abstract: We have measured the in-plane optical anisotropy (IPOA) of (1120) ZnO (a-plane) on (1012) sapphire (r-plane) by reflectance difference spectroscopy (RDS) at room temperature. Giant IPOA has been observed between the light polarized direction parallel and perpendicular to the c axis of ZnO, since the symmetry of a-plane is C2v. A sharp resonance has been observed near the fundamental band gap, which is induced by the polarization-depend band gap shift. The sharp line shape is attributed to the exciton transition. The spectra fitting and differential spectra indicate the polarization-depend band energies. The giant IPOA is possible enhanced by anisotropy strain along and perpendicular to the c axis in the a-plane.

Key words: ZnO, in-plane optical anisotropy, reflectance difference spectroscopy



[1]
Look D C. Recent advances in ZnO materials and devices. Mater Sci Eng B, 2001, 80:383 doi: 10.1016/S0921-5107(00)00604-8
[2]
Chen Y, Bagnall D M, Koh H, et al. Plasma assisted molecular beam epitaxy of ZnO on c-plane sapphire:growth and characterization. J Appl Phys, 1998, 84:3192 doi: 10.1063/1.368595
[3]
Look D C, Reynolds D C, Hemsky J W. et al. Production and annealing of electron irradiation damage in ZnO. Appl Phys Lett, 1999, 75:811 doi: 10.1063/1.124521
[4]
Gil B, Lefebvre P, Bretagnon T, et al. Spin-exchange interaction in ZnO-based quantum wells. Phys Rev B, 2006, 74:153302 doi: 10.1103/PhysRevB.74.153302
[5]
Tabares G, Hierro A, Vinter B, et al. Polarization-sensitive Schottky photodiodes based on a-plane ZnO/ZnMgO multiple quantum-wells. Appl Phys Lett, 2011, 99:071108 doi: 10.1063/1.3624924
[6]
Gorla C R, Emanetoglu N W, Liang S, et al. Structural, optical, and surface acoustic wave properties of epitaxial ZnO films grown on (0112) sapphire by metalorganic chemical vapor deposition. J Appl Phys, 1999, 85:2595 doi: 10.1063/1.369577
[7]
Chauveau J M, Vennegues P, Laugt M, et al. Interface structure and anisotropic strain relaxation of nonpolar wurtzite (1120) and (1010) orientations:ZnO epilayers grown on sapphire. J Appl Phys, 2008, 104:073535 doi: 10.1063/1.2996248
[8]
Cobet M, Cobet C, Wagner M R, et al. Polariton effects in the dielectric function of ZnO excitons obtained by ellipsometry. Appl Phys Lett, 2010, 96:031904 doi: 10.1063/1.3284656
[9]
Aspnes D E, Harbison J P, Studna A A, et al. Application of reflectance difference spectroscopy to molecular-beam epitaxy growth of GaAs and AlAs. J Vac Sci Technol A, 1988, 6:1327 doi: 10.1116/1.575694
[10]
Macdonald B F, Law J S, Cole R J, et al. Azimuth-dependent reflection anisotropy spectroscopy. J Appl Phys, 2003, 93:3320 doi: 10.1063/1.1544645
[11]
Rossow U, Goldhahn R, Fuhrmann D, et al. Reflectance difference spectroscopy RDS/RAS combined with spectroscopic ellipsometry for a quantitative analysis of optically anisotropic materials. Phys Status Solidi B, 2005, 242:2617 doi: 10.1002/(ISSN)1521-3951
[12]
Jellison G E, Boatner L A. Optical functions of uniaxial ZnO determined by generalized ellipsometry. Phys Rev B, 1998, 58:3586 doi: 10.1103/PhysRevB.58.3586
[13]
Le Toullec R, Piccioli N, Chervin J C. Optical properties of the band-edge exciton in GaSe crystals at 10 K. Phys Rev B, 1980, 22:6162 doi: 10.1103/PhysRevB.22.6162
[14]
Frederick F. Optical properties of solids. Academic Press New York, 1972 doi: 10.1119/1.1987434
[15]
Siah F, Yang Z, Tang Z K, et al. In-plane anisotropic strain of ZnO closely packed microcrystallites grown on tilted (0001) sapphire. J Appl Phys, 2000, 88:2480 doi: 10.1063/1.1287527
[16]
Chen Y H, Ye X L, Xu B, et al. Strong in-plane optical anisotropy of asymmetric (001) quantum wells. J Appl Phys, 2006, 99:096102 doi: 10.1063/1.2192150
Fig. 1.  (Color online) Counter plot of Im($\Delta r/r$) at different azimuth angles, the dashed lines indicate the positive or negative maximum of resonance amplitude, respectively.

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Fig. 2.  Im($\Delta r/r$) and Re($\Delta r/r$) between [$\overline{1}$100] and [0001] axes. The black hollow square line represents the imaginary part, and the red hollow circle line represents the real part of $\Delta r/r$, respectively.

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Fig. 3.  Im($\Delta r/r$) and its Lorentz line shape fitting. The red dashed and dotted line is the Lorentz fitting. The green dashed line is the one peak fitting labeled as peak 1. The blue dotted line is another peak fitting labeled as peak 2.

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Fig. 4.  Secondary derivative Im($\Delta r/r$) spectrum, peaks 1 and 2 correspond to the peak center.

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Fig. 5.  The calculated dielectric function $\varepsilon_{\perp 1}$, $\varepsilon_{\perp 2}$, $\varepsilon_{\parallel 1}$ and $\varepsilon_{\parallel 2}$. The squares in dashed lines show the region with unsatisfactory fitting.

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Fig. 6.  The calculated refractive index $n_{\perp}$ and $n_{\parallel}$, extinction coefficient $k_{\perp}$ and $k_{\parallel}$.

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Fig. 7.  Experimental (Exp) Im($\Delta r/r$) (solid line), Re($\Delta r/r$) (dash-dot line), calculated (Cal) Im($\Delta r/r$) (dotted line) and Re($\Delta r/r$) (dashed line).

DownLoad: Full-Size Img PowerPoint

Table 1.   The parameters of Lorentz peak fitting.

Table 2.   The parameters of the dielectric function fitting of ZnO.
[1]
Look D C. Recent advances in ZnO materials and devices. Mater Sci Eng B, 2001, 80:383 doi: 10.1016/S0921-5107(00)00604-8
[2]
Chen Y, Bagnall D M, Koh H, et al. Plasma assisted molecular beam epitaxy of ZnO on c-plane sapphire:growth and characterization. J Appl Phys, 1998, 84:3192 doi: 10.1063/1.368595
[3]
Look D C, Reynolds D C, Hemsky J W. et al. Production and annealing of electron irradiation damage in ZnO. Appl Phys Lett, 1999, 75:811 doi: 10.1063/1.124521
[4]
Gil B, Lefebvre P, Bretagnon T, et al. Spin-exchange interaction in ZnO-based quantum wells. Phys Rev B, 2006, 74:153302 doi: 10.1103/PhysRevB.74.153302
[5]
Tabares G, Hierro A, Vinter B, et al. Polarization-sensitive Schottky photodiodes based on a-plane ZnO/ZnMgO multiple quantum-wells. Appl Phys Lett, 2011, 99:071108 doi: 10.1063/1.3624924
[6]
Gorla C R, Emanetoglu N W, Liang S, et al. Structural, optical, and surface acoustic wave properties of epitaxial ZnO films grown on (0112) sapphire by metalorganic chemical vapor deposition. J Appl Phys, 1999, 85:2595 doi: 10.1063/1.369577
[7]
Chauveau J M, Vennegues P, Laugt M, et al. Interface structure and anisotropic strain relaxation of nonpolar wurtzite (1120) and (1010) orientations:ZnO epilayers grown on sapphire. J Appl Phys, 2008, 104:073535 doi: 10.1063/1.2996248
[8]
Cobet M, Cobet C, Wagner M R, et al. Polariton effects in the dielectric function of ZnO excitons obtained by ellipsometry. Appl Phys Lett, 2010, 96:031904 doi: 10.1063/1.3284656
[9]
Aspnes D E, Harbison J P, Studna A A, et al. Application of reflectance difference spectroscopy to molecular-beam epitaxy growth of GaAs and AlAs. J Vac Sci Technol A, 1988, 6:1327 doi: 10.1116/1.575694
[10]
Macdonald B F, Law J S, Cole R J, et al. Azimuth-dependent reflection anisotropy spectroscopy. J Appl Phys, 2003, 93:3320 doi: 10.1063/1.1544645
[11]
Rossow U, Goldhahn R, Fuhrmann D, et al. Reflectance difference spectroscopy RDS/RAS combined with spectroscopic ellipsometry for a quantitative analysis of optically anisotropic materials. Phys Status Solidi B, 2005, 242:2617 doi: 10.1002/(ISSN)1521-3951
[12]
Jellison G E, Boatner L A. Optical functions of uniaxial ZnO determined by generalized ellipsometry. Phys Rev B, 1998, 58:3586 doi: 10.1103/PhysRevB.58.3586
[13]
Le Toullec R, Piccioli N, Chervin J C. Optical properties of the band-edge exciton in GaSe crystals at 10 K. Phys Rev B, 1980, 22:6162 doi: 10.1103/PhysRevB.22.6162
[14]
Frederick F. Optical properties of solids. Academic Press New York, 1972 doi: 10.1119/1.1987434
[15]
Siah F, Yang Z, Tang Z K, et al. In-plane anisotropic strain of ZnO closely packed microcrystallites grown on tilted (0001) sapphire. J Appl Phys, 2000, 88:2480 doi: 10.1063/1.1287527
[16]
Chen Y H, Ye X L, Xu B, et al. Strong in-plane optical anisotropy of asymmetric (001) quantum wells. J Appl Phys, 2006, 99:096102 doi: 10.1063/1.2192150

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    Received: 19 May 2013 Revised: 25 June 2013 Online: Published: 01 December 2013

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      Article Navigation >  Journal of Semiconductors  > 2013  >  34(12): 122003
      Shujie Wu, Yonghai Chen, Xudong Qin, Hansong Gao, Jinling Yu, Laipan Zhu, Yuan Li, Kai Shi. Giant in-plane optical anisotropy of a-plane ZnO on r-plane sapphire[J]. Journal of Semiconductors, 2013, 34(12): 122003. doi: 10.1088/1674-4926/34/12/122003 S J Wu, Y H Chen, X D Qin, H S Gao, J L Yu, L P Zhu, Y Li, K Shi. Giant in-plane optical anisotropy of a-plane ZnO on r-plane sapphire[J]. J. Semicond., 2013, 34(12): 122003. doi: 10.1088/1674-4926/34/12/122003.Export: BibTex EndNote
      Citation:
      Shujie Wu, Yonghai Chen, Xudong Qin, Hansong Gao, Jinling Yu, Laipan Zhu, Yuan Li, Kai Shi. Giant in-plane optical anisotropy of a-plane ZnO on r-plane sapphire[J]. Journal of Semiconductors, 2013, 34(12): 122003. doi: 10.1088/1674-4926/34/12/122003

      S J Wu, Y H Chen, X D Qin, H S Gao, J L Yu, L P Zhu, Y Li, K Shi. Giant in-plane optical anisotropy of a-plane ZnO on r-plane sapphire[J]. J. Semicond., 2013, 34(12): 122003. doi: 10.1088/1674-4926/34/12/122003.
      Export: BibTex EndNote
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      Giant in-plane optical anisotropy of a-plane ZnO on r-plane sapphire

      doi: 10.1088/1674-4926/34/12/122003

      • Key Laboratory of Semiconductor Materials Science and Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China

      Funds:

      the State Key Development Program for Basic Research of China 2012CB921304

      the State Key Development Program for Basic Research of China 2013CB619306

      Project supported by the State Key Development Program for Basic Research of China (Nos. 2013CB619306, 2012CB921304), the National Natural Science Foundation of China (No. 60990313), and the National High Technology Research and Development Program of China (No. 2011AA03A101)

      the National Natural Science Foundation of China 60990313

      the National High Technology Research and Development Program of China 2011AA03A101

      More Information
      • Corresponding author: Wu Shujie, wusj@semi.ac.cn; Chen Yonghai, yhchen@semi.ac.cn
      • Received Date: 2013-05-19
      • Revised Date: 2013-06-25
      • Published Date: 2013-12-01

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