Self-Organized Quantum Dots for Memories

Self-Organized Quantum Dots for Memories
Author: Tobias Nowozin
Publisher: Springer Science & Business Media
Total Pages: 163
Release: 2013-10-01
Genre: Technology & Engineering
ISBN: 3319019708

Today’s semiconductor memory market is divided between two types of memory: DRAM and Flash. Each has its own advantages and disadvantages. While DRAM is fast but volatile, Flash is non-volatile but slow. A memory system based on self-organized quantum dots (QDs) as storage node could combine the advantages of modern DRAM and Flash, thus merging the latter’s non-volatility with very fast write times. This thesis investigates the electronic properties of and carrier dynamics in self-organized quantum dots by means of time-resolved capacitance spectroscopy and time-resolved current measurements. The first aim is to study the localization energy of various QD systems in order to assess the potential of increasing the storage time in QDs to non-volatility. Surprisingly, it is found that the major impact of carrier capture cross-sections of QDs is to influence, and at times counterbalance, carrier storage in addition to the localization energy. The second aim is to study the coupling between a layer of self-organized QDs and a two-dimensional hole gas (2DHG), which is relevant for the read-out process in memory systems. The investigation yields the discovery of the many-particle ground states in the QD ensemble. In addition to its technological relevance, the thesis also offers new insights into the fascinating field of nanostructure physics.

Self-Assembled Quantum Dots

Self-Assembled Quantum Dots
Author: Zhiming M Wang
Publisher: Springer Science & Business Media
Total Pages: 470
Release: 2007-11-29
Genre: Technology & Engineering
ISBN: 0387741917

This multidisciplinary book provides up-to-date coverage of carrier and spin dynamics and energy transfer and structural interaction among nanostructures. Coverage also includes current device applications such as quantum dot lasers and detectors, as well as future applications to quantum information processing. The book will serve as a reference for anyone working with or planning to work with quantum dots.

Resonant Tunneling Self-Assembled Quantum Dots for Memory Elements

Resonant Tunneling Self-Assembled Quantum Dots for Memory Elements
Author:
Publisher:
Total Pages: 15
Release: 1999
Genre:
ISBN:

Two main research topics were studied during this period: (1) Research on buried strain induced quantum dots (SIQDs) generated by self assembling quantum dot (QDs) layers. We investigated here a new type of quantum dots which are generated by the lateral band gap modulation of a quantum well GaAs/AlGaAs induced by a buried layer of self assembled quantum dots. Such SIQDs allow to move the OD confinement regime into the red region of the spectrum. The confinement energies for these SIQDs are function of the distance between the QDs layer and the QW and on the thickness of the QW. They also allow for a greater flexibility for integrating quantum dot devices in device structures. To this end, we have developed an exciton storage device based on quantum dot structures. The device uses pairs of SIQDs and QDs to store the exciton dissociated as an electron hole pair under an internal electric field. The stored e-h pair is restored as an exciton by applying a bias to the device. This method allows for exciton lifetimes of several seconds i.e., more than a billion times the lifetimes of excitons in normal QDs.

Quantum Dots

Quantum Dots
Author: Peter A. Ling
Publisher: Nova Publishers
Total Pages: 278
Release: 2005
Genre: Science
ISBN: 9781594544064

A quantum dot is a particle of matter so small that the addition or removal of an electron changes its properties in some useful way. All atoms are quantum dots, but multi-molecular combinations can have this characteristic. In biochemistry, quantum dots are called redox groups. In nanotechnology, they are called quantum bits or qubits. Quantum dots typically have dimensions measured in nanometers, where one nanometer is 10-9 meter or a millionth of a millimetre. The fields of biology, chemistry, computer science, and electronics are all of interest to researchers in nanotechnology. Other applications of quantum dots include nanomachines, neural networks, and high-density memory or storage media. Research is being carried out on nano-crystals, self-assembled dots, and gated structures. This book presents leading-edge research from around the world.

Capture and Relaxation in Self-Assembled Semiconductor Quantum Dots

Capture and Relaxation in Self-Assembled Semiconductor Quantum Dots
Author: Robson Ferreira
Publisher: Morgan & Claypool Publishers
Total Pages: 148
Release: 2016-02-23
Genre: Technology & Engineering
ISBN: 1681741539

This is an overview of different models and mechanisms developed to describe the capture and relaxation of carriers in quantum-dot systems. Despite their undisputed importance, the mechanisms leading to population and energy exchanges between a quantum dot and its environment are not yet fully understood. The authors develop a first-order approach to such effects, using elementary quantum mechanics and an introduction to the physics of semiconductors. The book results from a series of lectures given by the authors at the Master’s level.