PMID- 25965972
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20150915
LR  - 20150623
IS  - 1936-086X (Electronic)
IS  - 1936-0851 (Linking)
VI  - 9
IP  - 6
DP  - 2015 Jun 23
TI  - Exciton Fine-Structure Splitting in Self-Assembled Lateral InAs/GaAs Quantum-Dot 
      Molecular Structures.
PG  - 5741-9
LID - 10.1021/acsnano.5b01387 [doi]
AB  - Fine-structure splitting (FSS) of excitons in semiconductor nanostructures is a 
      key parameter that has significant implications in photon entanglement and 
      polarization conversion between electron spins and photons, relevant to quantum 
      information technology and spintronics. Here, we investigate exciton FSS in 
      self-organized lateral InAs/GaAs quantum-dot molecular structures (QMSs) 
      including laterally aligned double quantum dots (DQDs), quantum-dot clusters 
      (QCs), and quantum rings (QRs), by employing polarization-resolved 
      microphotoluminescence (muPL) spectroscopy. We find a clear trend in FSS between 
      the studied QMSs depending on their geometric arrangements, from a large FSS in 
      the DQDs to a smaller FSS in the QCs and QRs. This trend is accompanied by a 
      corresponding difference in the optical polarization directions of the excitons 
      between these QMSs, namely, the bright-exciton lines are linearly polarized 
      preferably along or perpendicular to the [11̅0] crystallographic axis in the DQDs 
      that also defines the alignment direction of the two constituting QDs, whereas in 
      the QCs and QRs, the polarization directions are randomly oriented. We attribute 
      the observed trend in the FSS to a significant reduction of the asymmetry in the 
      lateral confinement potential of the excitons in the QRs and QCs as compared with 
      the DQDs, as a result of a compensation between the effects of lateral shape 
      anisotropy and piezoelectric field. Our work demonstrates that FSS strongly 
      depends on the geometric arrangements of the QMSs, which effectively tune the 
      degree of the compensation effects and are capable of reducing FSS even in a 
      strained QD system to a limit similar to strain-free QDs. This approach provides 
      a pathway in obtaining high-symmetry quantum emitters desirable for realizing 
      photon entanglement and spintronic devices based on such nanostructures, 
      utilizing an uninterrupted epitaxial growth procedure without special 
      requirements for lattice-matched materials combinations, specific substrate 
      orientations, and nanolithography.
FAU - Fillipov, Stanislav
AU  - Fillipov S
AD  - daggerDepartment of Physics, Chemistry and Biology, Linkoping University, Linkoping 
      S-581 83, Sweden.
FAU - Puttisong, Yuttapoom
AU  - Puttisong Y
AD  - daggerDepartment of Physics, Chemistry and Biology, Linkoping University, Linkoping 
      S-581 83, Sweden.
FAU - Huang, Yuqing
AU  - Huang Y
AD  - daggerDepartment of Physics, Chemistry and Biology, Linkoping University, Linkoping 
      S-581 83, Sweden.
FAU - Buyanova, Irina A
AU  - Buyanova IA
AD  - daggerDepartment of Physics, Chemistry and Biology, Linkoping University, Linkoping 
      S-581 83, Sweden.
FAU - Suraprapapich, Suwaree
AU  - Suraprapapich S
AD  - double daggerDepartment of Electrical and Computer Engineering, University of California, La 
      Jolla, California 92093, United States.
FAU - Tu, Charles W
AU  - Tu CW
AD  - double daggerDepartment of Electrical and Computer Engineering, University of California, La 
      Jolla, California 92093, United States.
FAU - Chen, Weimin M
AU  - Chen WM
AD  - daggerDepartment of Physics, Chemistry and Biology, Linkoping University, Linkoping 
      S-581 83, Sweden.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20150515
PL  - United States
TA  - ACS Nano
JT  - ACS nano
JID - 101313589
OTO - NOTNLM
OT  - InAs/GaAs
OT  - fine structure splitting
OT  - microphotoluminescence
OT  - polarization
OT  - quantum dot
OT  - quantum-dot molecular structure
EDAT- 2015/05/13 06:00
MHDA- 2015/05/13 06:01
CRDT- 2015/05/13 06:00
PHST- 2015/05/13 06:00 [entrez]
PHST- 2015/05/13 06:00 [pubmed]
PHST- 2015/05/13 06:01 [medline]
AID - 10.1021/acsnano.5b01387 [doi]
PST - ppublish
SO  - ACS Nano. 2015 Jun 23;9(6):5741-9. doi: 10.1021/acsnano.5b01387. Epub 2015 May 
      15.