Sains Malaysiana 39(6)(2010): 1025–1030

Surface Morphology of In0.5Ga0.5 Quantum Dots Grown using Stranski-Krastanov Growth Mode

(Morfologi Permukaan Bintik Kuantum In_0.5Ga_0.5As yang ditumbuhkan  Menggunakan Mod Pertumbuhan Stranski-Krastanov)

Didik Aryanto & Zulkafli Othaman*

Department of Physics, Faculty of Science

Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia

Abd. Khamim Ismail & Amira Saryati Ameruddin

Ibnu Sina Institute for Fundamental Science Studies

Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia

Received: 9 November 2009 / Accepted: 11 February 2010

ABSTRACT

In this research an atomic force microscopy (AFM) study on self-assembled In_0.5Ga_0.5As/GaAs quantum dots (QDs) was performed. Surface morphology of self-assembled In_0.5Ga_0.5As QDs changes with different growth time. Increasing growth time increased the dots size and decreased the dots density. In addiditon, self-assembled In_0.5Ga_0.5As QDs was grown on In_0.1Ga_0.9As underlying layer with different after-growth AsH3 flow time during cooling-down. The underlying layer caused lattice strain relaxation in the QDs on the surface. Increasing the period of AsH3 flow during cooling-down reduced the diameter of the dots and increased the density. The migration of groups III species in the growth of In_0.5Ga_0.5As/GaAs system was influenced by AsH₃ flow during cooling-down period. This was due to the increase in surface population of active arsenic species. Underlying layer and the period of AsH₃ flow during cooling-down are the two key factors in the fabrication of small and dense In_0.5Ga_0.5As QDs.

Keywords: Quantum dots; Stranski-Krastanov

ABSTRAK

Dalam makalah ini, penyelidikan mikroskop daya atom kepada bintik kuantum In_0.5Ga_0.5As/GaAs yang terhimpun sendiri telah dilaksanakan. Morfologi permukaan bintik kuantum In_0.5Ga_0.5As/GaAs yang terhimpun sendiri berubah dengan masa penumbuhan yang berbeza. Peningkatan masa penumbuhan meningkatkan saiz tetapi merendahkan ketumpatan bintik. Disamping itu, bintik kuantum In_0.5Ga_0.5As /GaAs yang terkumpul sendiri telah ditumbuhkan di atas lapisan bawahan In_0.1Ga_0.9As dengan pengaliran AsH3 selepas penumbuhan yang berbeza semasa proses penyejukan. Lapisan bawahan telah merehatkan terikan kekisi di dalam bintik kuantum di atas permukaan. Penambahan tempoh pengaliran AsH3 semasa proses penyejukkan mengurangkan diameter bintik dan menambahkan ketumpatannya. Migrasi spesis kumpulan III dalam penumbuhan sistem In_0.5Ga_0.5As/GaAs adalah dipengaruhi oleh pengaliran AsH₃ semasa dalam tempoh proses penyejukkan. Ini adalah disebabkan peningkatan populasi permukaan spesies arsenik aktif. Lapisan bawahan dan tempoh pengaliran AsH₃ semasa proses penyejukkan merupakan dua faktor penting dalam fabrikasi bintik kuantum yang kecil dan padat.

Kata kunci: Bintik kuantum; Stranski-Krastanov

REFERENCES

Bimberg, D. 2005. Quantum dots for laser, amplifiers and computing. J. Appl. Phys. 38: 2055-2058

Chang, Z.Y., Jun, H.C., Ling, Y.X., Bo, X., Ding, D., Zheng, W.J. & Fa, L.Y. 2001. Structure and photoluminescence of InGaAs quantum dots formed on an InAlAs wetting layer. Chin. Phys. Lett. 18(10): 1411-1414.

Dimroth, F., Lanyi, P., Schubert, U. & Bett, A.W. 2000. MOVPE grown Ga1-xInxAs solar cells for GaInP/GaInAs tandem applications. J. Electronic Materials 29: 42-46.

Germann, T.D., Strittmatter, A., Kettler, Th., Posilovic, K., Pohl, U.W. & Bimberg, D. 2007. MOCVD of InGaAs/GaAs quantum dots for laser emitting close to 1.3 μm. J. Crystal Growth 298: 591-594.

Hanke, M., Grigoriev, D., Schmidbauer, M., Schӓfer, P., Kšhler, R., Pohl, U.W., Sellin, R. L., Bimberg, D., Zakharov, N.D. & Werner, P. 2004. Diffuse X-ray scattering of InGaAs/GaAs quantum dots. Physica E 21: 684-688.

Hsu, M.Y., Tang, S.F., Chiang, C.D., Su, C.C., Wang, L.C. & Kuo, C.T. 2006. Optical recombination emission characteristics and surface morphologies of InAs quantum dots grown on misoriented GaAs substrate by MOCVD. J. Thin Solid Films 498: 183-187.

Ishihara, T., Lee, S., Akabori, M., Motohisa, J. & Fukui, T. 2002. Dependence on In content of InGaAs quantum dots grown along GaAs multiatomic steps by MOVPE. J. Crystal Growth 237-239: 1476-1480.

Jiang, L., Li, S.S., Liu, W.S., Yeh, N.T. & Chyi, J.I. 2005. A two-stack, multi-color In0.5Ga0.5As/GaAs and lnAs/GaAs quantum dot infrared photodetector for long wavelength infrared detection. Infrared Physics & Technology 46: 249-256.

Jiang, W.H., Xu, H.Z., Xu, B., Wu, J., Ye, X. L., Liu, H.Y., Zhou, W., Sun, Z.Z., Li, Y.F., Liang, J.B. & Wang, Z.G. 1999. Fabrication of InGaAs quantum dots with an underlying InGaAlAs layer on GaAs(100) and high index substrates by molecular beam epitaxy. J. Crystal Growth 205: 607-612.

Joyce, P.B., Krzyewski, T.J., Steans, P.H., Bell, G.R., Neave, J.H. & Jones, T.S. 2001. Shape and surface morphology changes during the initial stages of encapsulation of InAs/GaAs quantum dots. J. Surface Science 492: 345-355.

Kim, J.O., Lee, S.J., Noh, S.K., Ryu, Y.H., Choi, S.M. & Choe, J.W. 2005. Laterally self-aligned InGaAs/GaAs quantum dots fabricated by using a multilayer stacking technique. J. Korean Physical Society 47(1): 94-99.

Kim, J.S. & Kim, J.S. 2006. Formation of InAs/GaAs quantum dots by alternating growth of InAs and GaAs with a quasi monolayer thickness. J. Korean Physical Society 49(1): 195-198.

Kitamura, M., Nishioka, M., Schur, R. & Arakawa. Y. 1997. Direct observation of the transition from a 2D layer to 3D islands at the initial stage of InGaAs growth on GaAs by AFM. J. Crystal Growth 170: 563-567.

Kita, T., Yamashita, K., Tango, H. & Nishino, T. 2000. Dynamic process of two-dimensional InAs growth in Stranski-Krastanov mode. Physica E 7: 891-895.

Kladko, V.P., Strelchuk, V.V., Kolomys, A.F., Slobodian, M.V., Mazur, Y.I., Wang, Z.H. M., Kunets, V.P. & Salamo. G.J. 2007. Microstructural aspects of nucleation and growth of (In,Ga)As/GaAs(100) island with low indium content. J. Electronic Materials 36: 1555-1560.

Leon, R., Wellman, J., Liao, X. Z., Zou, J. & Cyokayne, D.J.H. 2000. Adatom condensation and quantum dots sizes in InGaAs/GaAs(001). Appl. Phys. Lett. 76(12): 1558-1560.

Ng, J. & Missous, M. 1996. Improvement of Stacked self-assembled InAs/GaAs Quantum Dots Structures for 1.3 μm Applications. J. Microelectronics 37: 1446-1450.

Offermans, P., Koenraad, P.M., Wolter, J.H., Pierz, K., Roy, M. & Maksym, P.A. 2005. Formation of InAs quantum dots and wetting layers in GaAs and AlAs analyzed by cross-sectional scanning tunneling microscopy. Physica E 26: 236-240.

Osborn, K.D., Keller, M.W. & Mirin, R.P. 2004. Single-electron transistor spectroscopy of InGaAs self-assembled quantum dots. Physica E 21: 501-505.

Riel, B.J., Hinzer, K., Moisa, S., Fraser, J., Finnie, P., Piercy, P., Fafard, S. & Wasilewski, Z. 2002. InAs/GaAs(100) self-assembled quantum dots, arsenic pressure and capping effects. J. Crystal Growth 236: 145-154.

Sears, K., Mokkapati, S., Tan, H.H. & Jagadish, C. 2008. In(Ga)As/GaAs quantum dots grown by MOCVD for opto-electronic device applications. In Self-assembled quantum dots, edited by Z.M. Wang. New York: Springer pp. 359-403.

Son , J.Y. & Cho, J.H. 2008. Stranski-Krastanov (SK) growth mode of layered g-Na0.7CoO2 on (111) SrTiO₃ substrate. J. Crystal Growth 310(12): 3093-3096.

Srinivasan, T., Singha, S.N., Tiwari, U., Sharma, R.K., Muralidharan, R., Rao, D.V.S, Balamuralikrishnan, R. & Muraleedharan, K. 2005. Structural and photoluminescence characteristics of molecular beam epitaxy-grown vertically aligned In_0.33Ga_0.67As/GaAs quantum dots. J. Crystal Growth 280: 378-384.

Wang, B., Chua, S-J., Dong, J. & Wang, Y. 2006. Highly strained quantum structures grown on GaAs (001) vicinal substrate by MOCVD. J. Crystal Growth 288: 61-64.

Xie, Q., Brown, J.L., Jones, R.L. & Nostrand, J.E.V. 1999. Shape stabilization and size equalization of InGaAs self-organized quantum dots. J. Electronic Materials 28(12): L42-L45.

Xu, M. C., Temko, Y., Suzuki, T. & Jacobi, K. 2005. InAs wetting layer evolution on GaAs(001). J. Surface Science 580: 30-38.

Xu, S.J., Chua, S.J., Mei, T., Wang, X.C., Zhang, X.H., Karunasiri, G., Fan, W.J., Wang, C.H., Jiang, J., Wang, S. & Xie, X.G. 1998. Characteristics of InGaAs quantum dot infrared photodetectors. Appl. Phys. Lett. 73: 3153-3155.

*Corresponding author; e-mail: zulothaman@gmail.com