Quantum Dots, Semiconductor: Site-Controlled Self-organization


K. Asakawa Femtosecond Technology Research Association (FESTA)

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The spontaneous formation of nanoscale islands in strained-layer epitaxy, represented by Stranski–Krastanov mode growth, has been widely studied as a simple and efficient method for producing semiconductor quantum dots. In such a self-organizing approach, quantum dots form randomly on surfaces. If the formation sites of individual quantum dots can be specified, they can be arranged in various configurations, from a single dot to regular, dense, and even coupled dot arrays, and dot placement can be restricted to specific regions, enabling the development of novel electronic and optical devices.

This article proposes a technique for controlling the self-organization sites of individual quantum dots using scanning tunneling microscope (STM) probe-assisted nanolithography and self-organizing molecular beam epitaxy (MBE). Two-dimensional (2-D) and three-dimensional (3-D) arrays of InAs site-controlled quantum dots (SCQDs) are successfully fabricated on GaAs substrates with nanoscale pitch and precision. Photoluminescence from the SCQD arrays is investigated at room temperature. The tip repositioning function of the STM system reveals the growth mode of the SCQDs.