Revealing surface-state transport in ultrathin topological crystalline insulator SnTe films
SnTe is a topological crystalline insulator that exhibits crystal symmetry protected topological surface states (SS), which are useful for the development of novel devices, such as low-dissipation transistors. However, major obstacles remain to probe the SS and realize the application of SnTe and ot...
| Main Authors: | , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
AIP Publishing LLC
2019-05-01
|
| Series: | APL Materials |
| Online Access: | http://dx.doi.org/10.1063/1.5096279 |
| _version_ | 1811216333607534592 |
|---|---|
| author | Ke Zou Stephen D. Albright Omur E. Dagdeviren M. D. Morales-Acosta Georg H. Simon Chao Zhou Subhasish Mandal Sohrab Ismail-Beigi Udo D. Schwarz Eric I. Altman Frederick J. Walker Charles H. Ahn |
| author_facet | Ke Zou Stephen D. Albright Omur E. Dagdeviren M. D. Morales-Acosta Georg H. Simon Chao Zhou Subhasish Mandal Sohrab Ismail-Beigi Udo D. Schwarz Eric I. Altman Frederick J. Walker Charles H. Ahn |
| author_sort | Ke Zou |
| collection | DOAJ |
| description | SnTe is a topological crystalline insulator that exhibits crystal symmetry protected topological surface states (SS), which are useful for the development of novel devices, such as low-dissipation transistors. However, major obstacles remain to probe the SS and realize the application of SnTe and other topological insulators. Due to unintentional doping by Sn vacancies, bulk conduction may overwhelm the transport through SS in SnTe. Synthesis of SnTe films thin enough to suppress bulk conduction has proven difficult due to the formation of discontinuous domain structures. By introducing a novel deposition method that builds upon molecular beam epitaxy, we achieve ultrathin continuous films of single-orientation SnTe (001) on SrTiO3 (STO) (001) substrates. We separate the carrier concentrations in the bulk and in the SS and discover that conduction through the SS dominates (a majority of hole carriers occupy the SS) in films thinner than 40 unit cells, with a large temperature independent hole density of SS nS = 5 × 1014 cm−2. Unlike the depletion of SS carriers observed at the vacuum/SnTe interface that inhibits topological behavior, we show that SS carriers are buried and protected from depletion at the SnTe/STO interface, which is enabled by the relatively large bandgap of STO and its favorable band alignment with SnTe. This work provides an important pathway for probing and realizing SS transport in SnTe and other TIs even when bulk conduction coexists. |
| first_indexed | 2024-04-12T06:37:29Z |
| format | Article |
| id | doaj.art-eb697bdda4b9452ca379bc5fcc145643 |
| institution | Directory Open Access Journal |
| issn | 2166-532X |
| language | English |
| last_indexed | 2024-04-12T06:37:29Z |
| publishDate | 2019-05-01 |
| publisher | AIP Publishing LLC |
| record_format | Article |
| series | APL Materials |
| spelling | doaj.art-eb697bdda4b9452ca379bc5fcc1456432022-12-22T03:43:51ZengAIP Publishing LLCAPL Materials2166-532X2019-05-0175051106051106-610.1063/1.5096279007905APMRevealing surface-state transport in ultrathin topological crystalline insulator SnTe filmsKe Zou0Stephen D. Albright1Omur E. Dagdeviren2M. D. Morales-Acosta3Georg H. Simon4Chao Zhou5Subhasish Mandal6Sohrab Ismail-Beigi7Udo D. Schwarz8Eric I. Altman9Frederick J. Walker10Charles H. Ahn11Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USACenter for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520, USACenter for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520, USADepartment of Applied Physics, Yale University, New Haven, Connecticut 06520, USACenter for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520, USACenter for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520, USADepartment of Applied Physics, Yale University, New Haven, Connecticut 06520, USADepartment of Applied Physics, Yale University, New Haven, Connecticut 06520, USACenter for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520, USACenter for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520, USADepartment of Applied Physics, Yale University, New Haven, Connecticut 06520, USADepartment of Applied Physics, Yale University, New Haven, Connecticut 06520, USASnTe is a topological crystalline insulator that exhibits crystal symmetry protected topological surface states (SS), which are useful for the development of novel devices, such as low-dissipation transistors. However, major obstacles remain to probe the SS and realize the application of SnTe and other topological insulators. Due to unintentional doping by Sn vacancies, bulk conduction may overwhelm the transport through SS in SnTe. Synthesis of SnTe films thin enough to suppress bulk conduction has proven difficult due to the formation of discontinuous domain structures. By introducing a novel deposition method that builds upon molecular beam epitaxy, we achieve ultrathin continuous films of single-orientation SnTe (001) on SrTiO3 (STO) (001) substrates. We separate the carrier concentrations in the bulk and in the SS and discover that conduction through the SS dominates (a majority of hole carriers occupy the SS) in films thinner than 40 unit cells, with a large temperature independent hole density of SS nS = 5 × 1014 cm−2. Unlike the depletion of SS carriers observed at the vacuum/SnTe interface that inhibits topological behavior, we show that SS carriers are buried and protected from depletion at the SnTe/STO interface, which is enabled by the relatively large bandgap of STO and its favorable band alignment with SnTe. This work provides an important pathway for probing and realizing SS transport in SnTe and other TIs even when bulk conduction coexists.http://dx.doi.org/10.1063/1.5096279 |
| spellingShingle | Ke Zou Stephen D. Albright Omur E. Dagdeviren M. D. Morales-Acosta Georg H. Simon Chao Zhou Subhasish Mandal Sohrab Ismail-Beigi Udo D. Schwarz Eric I. Altman Frederick J. Walker Charles H. Ahn Revealing surface-state transport in ultrathin topological crystalline insulator SnTe films APL Materials |
| title | Revealing surface-state transport in ultrathin topological crystalline insulator SnTe films |
| title_full | Revealing surface-state transport in ultrathin topological crystalline insulator SnTe films |
| title_fullStr | Revealing surface-state transport in ultrathin topological crystalline insulator SnTe films |
| title_full_unstemmed | Revealing surface-state transport in ultrathin topological crystalline insulator SnTe films |
| title_short | Revealing surface-state transport in ultrathin topological crystalline insulator SnTe films |
| title_sort | revealing surface state transport in ultrathin topological crystalline insulator snte films |
| url | http://dx.doi.org/10.1063/1.5096279 |
| work_keys_str_mv | AT kezou revealingsurfacestatetransportinultrathintopologicalcrystallineinsulatorsntefilms AT stephendalbright revealingsurfacestatetransportinultrathintopologicalcrystallineinsulatorsntefilms AT omuredagdeviren revealingsurfacestatetransportinultrathintopologicalcrystallineinsulatorsntefilms AT mdmoralesacosta revealingsurfacestatetransportinultrathintopologicalcrystallineinsulatorsntefilms AT georghsimon revealingsurfacestatetransportinultrathintopologicalcrystallineinsulatorsntefilms AT chaozhou revealingsurfacestatetransportinultrathintopologicalcrystallineinsulatorsntefilms AT subhasishmandal revealingsurfacestatetransportinultrathintopologicalcrystallineinsulatorsntefilms AT sohrabismailbeigi revealingsurfacestatetransportinultrathintopologicalcrystallineinsulatorsntefilms AT udodschwarz revealingsurfacestatetransportinultrathintopologicalcrystallineinsulatorsntefilms AT ericialtman revealingsurfacestatetransportinultrathintopologicalcrystallineinsulatorsntefilms AT frederickjwalker revealingsurfacestatetransportinultrathintopologicalcrystallineinsulatorsntefilms AT charleshahn revealingsurfacestatetransportinultrathintopologicalcrystallineinsulatorsntefilms |