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

Diserahkan: 9 November 2009 / Diterima: 11 Februari 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

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*Pengarang untuk surat-menyurat; e-mail: zulothaman@gmail.com