A mean field approach to Coulomb blockade for a disordered assembly of quantum dots

Pramana

Akashdeep Kamra¹  Vijay A Singh2²  Praveen Pathak² 

[1] Department of Electrical Engineering, Indian Institute of Technology, Kanpur 208 016, India$$;Homi Bhabha Centre for Science Education (TIFR), V.N. Purav Marg, Mankhurd, Mumbai 400 088, India$$

关键词: Quantum dots;    artificial atoms;    Coulomb blockade;    disorder in nanostructures.;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

The Coulomb blockade (CB) in quantum dots (QDs) is by now well documented. It has been used to guide the fabrication of single electron transistors. Even the most sophisticated techniques for synthesizing QDs (e.g. MOCVD/MBE) result in an assembly in which a certain amount of disorder is inevitable. On the other hand, theoretical approaches to CB limit themselves to an analysis of a single QD. In the present work we consider two types of disorders: (i) size disorder; e.g. QDs have a distribution of sizes which could be unimodal or bimodal in nature. (ii) Potential disorder with the confining potential assuming a variety of shapes depending on growth condition and external fields. We assume a Gaussian distribution in disorder in both size and potential and employ a simplified mean field theory. To do this we rely on the scaling laws for the CB (also termed as Hubbard 𝑈) obtained for an isolated QD [1]. We analyze the distribution in the Hubbard 𝑈 as a consequence of disorder and observe that Coulomb blockade is partially suppressed by the disorder. Further, the distribution in 𝑈 is a skewed Gaussian with enhanced broadening.

【 授权许可】

Unknown