Abstract
High bulk conductance obscures the behavior of surface states in the prototypical topological insulators Bi2Te3 and Bi2Se3. However, ternary phases of Bi2Te3-ySey with balanced donor and acceptor levels may lead to large bulk resistivity, allowing for the observation of the surface states. Additionally, the contribution of the bulk conductance may be further suppressed by nanostructuring, increasing the surface-to-volume ratio. Herein we report the synthesis of a ternary tetradymite newly confined to two dimensions. Ultra-thin large-area stable nanosheets were fabricated via evaporative thinning of a Bi2Te2.9Se0.1 original phase. Owing to vapor pressure differences, a compositional shift to a final Bi-rich phase is observed. The Se/Te ratio of the nanosheet increases tenfold, due to the higher stability of the Bi-Se bonds. Hexagonal crystal symmetry is maintained despite dramatic changes in thickness and stoichiometry. Given that small variations in stoichiometry of this ternary system can incur large changes in carrier concentration and switch majority carrier type, the large compositional shifts found in this case imply that compositional analysis of similar CVD and PVD grown materials is critical to correctly interpret topological insulator performance. Further, the characterization techniques deployed, including STEM-EDS and ToF-SIMS, serve as a case study in determining such compositional shifts in two-dimensional form.
| Original language | English |
|---|---|
| Pages (from-to) | 138-144 |
| Number of pages | 7 |
| Journal | Journal of Crystal Growth |
| Volume | 436 |
| DOIs | |
| Publication status | Published - Feb 15 2016 |
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Keywords
- A1. Solid solutions
- A3. Evaporative thinning
- A3. Physical vapor deposition processes
- B1. Nanomaterials
- B2. Semiconducting ternary compounds
- B2. Topological insulators
ASJC Scopus subject areas
- Condensed Matter Physics
- Materials Chemistry
- Inorganic Chemistry
Cite this
Two-dimensional bismuth-rich nanosheets through the evaporative thinning of Se-doped Bi2Te3 . / Hanson, Eve D.; Shi, Fengyuan; Chasapis, Thomas C.; Kanatzidis, Mercouri G; Dravid, Vinayak P.
In: Journal of Crystal Growth, Vol. 436, 15.02.2016, p. 138-144.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Two-dimensional bismuth-rich nanosheets through the evaporative thinning of Se-doped Bi2Te3
AU - Hanson, Eve D.
AU - Shi, Fengyuan
AU - Chasapis, Thomas C.
AU - Kanatzidis, Mercouri G
AU - Dravid, Vinayak P.
PY - 2016/2/15
Y1 - 2016/2/15
N2 - High bulk conductance obscures the behavior of surface states in the prototypical topological insulators Bi2Te3 and Bi2Se3. However, ternary phases of Bi2Te3-ySey with balanced donor and acceptor levels may lead to large bulk resistivity, allowing for the observation of the surface states. Additionally, the contribution of the bulk conductance may be further suppressed by nanostructuring, increasing the surface-to-volume ratio. Herein we report the synthesis of a ternary tetradymite newly confined to two dimensions. Ultra-thin large-area stable nanosheets were fabricated via evaporative thinning of a Bi2Te2.9Se0.1 original phase. Owing to vapor pressure differences, a compositional shift to a final Bi-rich phase is observed. The Se/Te ratio of the nanosheet increases tenfold, due to the higher stability of the Bi-Se bonds. Hexagonal crystal symmetry is maintained despite dramatic changes in thickness and stoichiometry. Given that small variations in stoichiometry of this ternary system can incur large changes in carrier concentration and switch majority carrier type, the large compositional shifts found in this case imply that compositional analysis of similar CVD and PVD grown materials is critical to correctly interpret topological insulator performance. Further, the characterization techniques deployed, including STEM-EDS and ToF-SIMS, serve as a case study in determining such compositional shifts in two-dimensional form.
AB - High bulk conductance obscures the behavior of surface states in the prototypical topological insulators Bi2Te3 and Bi2Se3. However, ternary phases of Bi2Te3-ySey with balanced donor and acceptor levels may lead to large bulk resistivity, allowing for the observation of the surface states. Additionally, the contribution of the bulk conductance may be further suppressed by nanostructuring, increasing the surface-to-volume ratio. Herein we report the synthesis of a ternary tetradymite newly confined to two dimensions. Ultra-thin large-area stable nanosheets were fabricated via evaporative thinning of a Bi2Te2.9Se0.1 original phase. Owing to vapor pressure differences, a compositional shift to a final Bi-rich phase is observed. The Se/Te ratio of the nanosheet increases tenfold, due to the higher stability of the Bi-Se bonds. Hexagonal crystal symmetry is maintained despite dramatic changes in thickness and stoichiometry. Given that small variations in stoichiometry of this ternary system can incur large changes in carrier concentration and switch majority carrier type, the large compositional shifts found in this case imply that compositional analysis of similar CVD and PVD grown materials is critical to correctly interpret topological insulator performance. Further, the characterization techniques deployed, including STEM-EDS and ToF-SIMS, serve as a case study in determining such compositional shifts in two-dimensional form.
KW - A1. Solid solutions
KW - A3. Evaporative thinning
KW - A3. Physical vapor deposition processes
KW - B1. Nanomaterials
KW - B2. Semiconducting ternary compounds
KW - B2. Topological insulators
UR - http://www.scopus.com/inward/record.url?scp=84951326102&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84951326102&partnerID=8YFLogxK
U2 - 10.1016/j.jcrysgro.2015.11.033
DO - 10.1016/j.jcrysgro.2015.11.033
M3 - Article
AN - SCOPUS:84951326102
VL - 436
SP - 138
EP - 144
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
SN - 0022-0248
ER -