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Title: Phonon blocking by two dimensional electron gas in polar CdTe/PbTe heterojunctions

Abstract

Narrow-gap lead telluride crystal is an important thermoelectric and mid-infrared material in which phonon functionality is a critical issue to be explored. In this Letter, efficient phonon blockage by forming a polar CdTe/PbTe heterojunction is explicitly observed by Raman scattering. The unique phonon screening effect can be interpreted by recent discovery of high-density two dimensional electrons at the polar CdTe/PbTe(111) interface which paves a way for design and fabrication of thermoelectric devices.

Authors:
; ; ; ; ; ; ; ;  [1]
  1. Department of Physics and State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China)
Publication Date:
OSTI Identifier:
22262777
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 16; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CADMIUM TELLURIDES; CHANNELING; ELECTRON GAS; ELECTRONS; HETEROJUNCTIONS; LEAD TELLURIDES; PHONONS; RAMAN EFFECT

Citation Formats

Zhang, Bingpo, Cai, Chunfeng, Zhu, He, Wu, Feifei, Ye, Zhenyu, Chen, Yongyue, Li, Ruifeng, Kong, Weiguang, and Wu, Huizhen, E-mail: hzwu@zju.edu.cn. Phonon blocking by two dimensional electron gas in polar CdTe/PbTe heterojunctions. United States: N. p., 2014. Web. doi:10.1063/1.4872168.
Zhang, Bingpo, Cai, Chunfeng, Zhu, He, Wu, Feifei, Ye, Zhenyu, Chen, Yongyue, Li, Ruifeng, Kong, Weiguang, & Wu, Huizhen, E-mail: hzwu@zju.edu.cn. Phonon blocking by two dimensional electron gas in polar CdTe/PbTe heterojunctions. United States. doi:10.1063/1.4872168.
Zhang, Bingpo, Cai, Chunfeng, Zhu, He, Wu, Feifei, Ye, Zhenyu, Chen, Yongyue, Li, Ruifeng, Kong, Weiguang, and Wu, Huizhen, E-mail: hzwu@zju.edu.cn. Mon . "Phonon blocking by two dimensional electron gas in polar CdTe/PbTe heterojunctions". United States. doi:10.1063/1.4872168.
@article{osti_22262777,
title = {Phonon blocking by two dimensional electron gas in polar CdTe/PbTe heterojunctions},
author = {Zhang, Bingpo and Cai, Chunfeng and Zhu, He and Wu, Feifei and Ye, Zhenyu and Chen, Yongyue and Li, Ruifeng and Kong, Weiguang and Wu, Huizhen, E-mail: hzwu@zju.edu.cn},
abstractNote = {Narrow-gap lead telluride crystal is an important thermoelectric and mid-infrared material in which phonon functionality is a critical issue to be explored. In this Letter, efficient phonon blockage by forming a polar CdTe/PbTe heterojunction is explicitly observed by Raman scattering. The unique phonon screening effect can be interpreted by recent discovery of high-density two dimensional electrons at the polar CdTe/PbTe(111) interface which paves a way for design and fabrication of thermoelectric devices.},
doi = {10.1063/1.4872168},
journal = {Applied Physics Letters},
number = 16,
volume = 104,
place = {United States},
year = {Mon Apr 21 00:00:00 EDT 2014},
month = {Mon Apr 21 00:00:00 EDT 2014}
}
  • Quantum oscillations are observed in the 2DEG system at the interface of novel heterostructures, PbTe/CdTe (111), with nearly identical lattice parameters (a PbTe = 0.6462 nm, a CdTe = 0.648 nm) but very different lattice structures (PbTe: rock salt, CdTe: zinc blende). The 2DEG formation mechanism, a mismatch in the bonding configurations of the valence electrons at the interface, is uniquely different from the other known 2DEG systems. The aberration-corrected scanning transmission electron microscope (AC-STEM) characterization indicates an abrupt interface without cation interdiffusion due to a large miscibility gap between the two constituent materials. As a result, electronic transport measurementsmore » under magnetic field up to 60 T, with the observation of Landau level filling factor ν = 1, unambiguously reveal a π Berry phase, suggesting the Dirac Fermion nature of the 2DEG at the heterostructure interface, and the PbTe/CdTe heterostructure being a new candidate for 2D topological crystalline insulators.« less
  • Here, quantum oscillations are observed in the 2DEG system at the interface of novel heterostructures, PbTe/CdTe (111), with nearly identical lattice parameters (a PbTe = 0.6462 nm, a CdTe = 0.648 nm) but very different lattice structures (PbTe: rock salt, CdTe: zinc blende). The 2DEG formation mechanism, a mismatch in the bonding configurations of the valence electrons at the interface, is uniquely different from the other known 2DEG systems. The aberration-corrected scanning transmission electron microscope (AC-STEM) characterization indicates an abrupt interface without cation interdiffusion due to a large miscibility gap between the two constituent materials. Electronic transport measurements under magneticmore » field up to 60 T, with the observation of Landau level filling factor ν = 1, unambiguously reveal a π Berry phase, suggesting the Dirac Fermion nature of the 2DEG at the heterostructure interface, and the PbTe/CdTe heterostructure being a new candidate for 2D topological crystalline insulators.« less
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  • Through systematic control of the Nd concentration, we show that the carrier density of the twodimensional electron gas (2DEG) in SrTiO3=NdTiO3=SrTiO3 ð001Þ can be modulated over a wide range. We also demonstrate that the NdTiO3 in heterojunctions without a SrTiO3 cap is degraded by oxygen absorption from air, resulting in the immobilization of donor electrons that could otherwise contribute to the 2DEG. This system is, thus, an ideal model to understand and control the insulator-to-metal transition in a 2DEG based on both environmental conditions and film-growth processing parameters.