Electronic confinement in self-assembled quantum dots (SAQD) modeled with a new interfacial capping layer

• Published in: Computational materials science 2010-07, Vol.49 (1), p.S54-S59
• Main Authors: Lam, A.W., Ng, T.Y.
• Format: Article
• Language: English
• Subjects: Band gap energies; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Finite element method; Interfacial capping layer; Physics; Pyramidal quantum dot; Quantum dots
• ISSN: 0927-0256; 1879-0801
• DOI: 10.1016/j.commatsci.2010.01.043

Quantum dots exhibit interesting structural and electronic properties due to quantum size effect at nanoscale. They are used as bio-tags to emit different color light with different dot sizes, and quantum dots are currently extensively studied for application as quantum devices taking advantage of the “artificial atom” properties such as their discrete energies, electron spins and quantum transport energies. Quantum dots generally exist as spheroidal nanoclusters in suspension, and pyramidal or conical heterostructures on substrate. The self-assembled semiconductor quantum dots are grown on the wetting layer of a few monolayer thickness and subsequently capped with a strain-reduction layer covering the dots to stabilize them. We study the indium arsenide/gallium arsenide self-assembled quantum dots modeled with a wetting layer between the quantum dot and substrate, and the strain-reducing capping layer above the quantum dot. We introduce a new model with an interfacial layer between the quantum dot and the capping layer and investigate the effective mechanical and electronic properties using the finite element method and deformation potential theory. The modified strains along the [0 0 1] direction through the center to the tip of the pyramid of the quantum dots are obtained for different elastic modulus of the interfacial capping layer. We evaluate that the interfacial capping layer with higher elastic modulus correctly depicts the ground state band gap energy.