Quantum dots: Mid-infrared luminescence, (110) growth, single-dot electroluminescence, and cleaved-edge alignment

The first half of this dissertation describes the development of quantum dot mid-infrared light emitters. The design, modelling, growth, and characterization of these devices is explained. We show the results from the first unipolar, electrically-pumped mid-infrared quantum dot emitter. Using a program designed to model electron transmission through semiconductor heterostructures, our initial devices were improved so that total light emission intensity was increased by an order of magnitude. Additionally, possible future improvements to these devices and the feasibility of fabricating a quantum dot mid-infrared laser are discussed.; The second half of the thesis concerns quantum dot growth on (110) GaAs. This section of the work is divided into three subsections. The first, Chapter 3: "(110) Quantum Dot Growth", discusses the growth of InAs on (110) GaAs and explains the growth process for quantum dot formation on this surface. In addition, we describe the methods used to determine that dots had indeed formed on the (110) surface. This work resulted in the first reports of InAs quantum dot growth on (I10) GaAs.; It was discovered that InAs dots form with extremely low densities on the (110) surface. Such low dot densities are ideal for the fabrication of single-dot electroluminescent devices, the subject of the second subsection of this half of the thesis (Chapter 4: "Single Dot Electroluminescence"). Diodes containing InAs dots were grown on (110) GaAs and used to fabricate fiber-coupled, single-dot electroluminescent devices. We discuss the fabrication and characterization of these devices and suggest improvements in the device design which could lead to more efficient emitters.; Chapter 5: "Cleaved Edge Overgrowth of Quantum Dots", concludes our discussion of (110) quantum dots by describing the growth of InAs on the cleaved edges of samples containing strained InGaAs quantum wells. Because GaAs cleaves along the (110) facet, the ability to grow dots on (110) GaAs was a prerequisite for this work. The process of cleaved-edge overgrowth and its use in the formation of strain-aligned quantum dots is discussed, as are certain unexpected results from this experiment and proposed methods to improve dot formation and alignment on the cleaved edge.