Universität zu Köln

Boemerich, Thomas, Lux, Jonathan, Feng, Qingyufei Terenz and Rosch, Achim ORCID: 0000-0002-6586-5721 (2017). Length scale of puddle formation in compensation-doped semiconductors and topological insulators. Phys. Rev. B, 96 (7). COLLEGE PK: AMER PHYSICAL SOC. ISSN 2469-9969

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Abstract

In most semiconductors and insulators the presence of a small density of charged impurities cannot be avoided, but their effect can be reduced by compensation doping, i.e., by introducing defects of opposite charge. Screening in such a system leads to the formation of electron-hole puddles, which dominate bulk transport, as first recognized by Efros and Shklovskii. Metallic surface states of topological insulators (TIs) contribute extra screening channels, suppressing puddles. We investigate the typical length l(P), which determines the distance between puddles and the suppression of puddle formation close to metallic surfaces in the limit where the gap Delta is much larger than the typical Coulomb energy E-c of neighboring dopants Delta >> Ec. In particular, this is relevant for three-dimensional Bi-based topological insulators, where Delta/E-c similar to 100. Scaling arguments predict l(P) similar to (Delta/Ec)(2). In contrast, we find numerically that l(P) is much smaller and grows in an extended crossover regime approximately linearly with Delta/Ec for numerically accessible values Delta/Ec less than or similar to 35. We show how a quantitative scaling argument can be used to extrapolate to larger Delta/Ec, where l(P) similar to (Delta/Ec)(2) / ln(Delta/Ec). Our results can be used to predict a characteristic thickness of TI thin films, below which the sample quality is strongly enhanced.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Boemerich, Thomas UNSPECIFIED UNSPECIFIED UNSPECIFIED Lux, Jonathan UNSPECIFIED UNSPECIFIED UNSPECIFIED Feng, Qingyufei Terenz UNSPECIFIED UNSPECIFIED UNSPECIFIED Rosch, Achim UNSPECIFIED orcid.org/0000-0002-6586-5721 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-221688
DOI:	10.1103/PhysRevB.96.075204
Journal or Publication Title:	Phys. Rev. B
Volume:	96
Number:	7
Date:	2017
Publisher:	AMER PHYSICAL SOC
Place of Publication:	COLLEGE PK
ISSN:	2469-9969
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute for Theoretical Physics
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language GRAPHENE; SURFACE; GAP Multiple languages Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/22168