Comprehensive study on critical role of surface oxygen vacancies for 2DEG formation and annihilation in LaAlO3/SrTiO3 heterointerfaces

Seon Young Moon, Cheon Woo Moon, Hye Jung Chang, Taemin Kim, Chong Yun Kang, Heon-Jin Choi, Jin Sang Kim, Seung Hyub Baek, Ho Won Jang

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Here we report comprehensive study of 2DEG at a-LAO/STO interfaces in comparison with 2DEG at crystalline LaAlO3 (c-LAO)/STO interfaces. We observe that the oxygen deficient environment during the deposition of LAO overlayer is essentially required to create 2DEG at LAO/STO interface regardless of growth temperature from 25°C to 700°C, indicating that the oxygen-poor condition in the system is more important than the crystallinity of LAO layer. The critical thickness (2.6 nm) of 2DEG formation at a-LAO/STO heterostructure is thicker than (1.6 nm) that at c-LAO/STO. Upon ex-situ annealing at 300°C under 300 mTorr of oxygen pressure, 2DEG at a-LAO/STO interface is annihilated, while that in c-LAO/STO interface is still maintained. With combing these findings and scanning transmission electron microscope (STEM) analysis, we suggest that oxygen vacancies at the LAO surface is attributed to the origin of 2DEG formation at the LAO/STO and the crystallinity of the LAO overlayer plays a critical role in the annihilation of 2DEG at a-LAO/STO interface rather than in the formation of 2DEG. This work provides a framework to understand the importance of prohibiting the LAO surface from being oxidized for achieving thermally stable 2DEG at a-LAO/STO interface. [Figure not available: see fulltext.]

Original languageEnglish
Pages (from-to)243-250
Number of pages8
JournalElectronic Materials Letters
Volume12
Issue number2
DOIs
Publication statusPublished - 2016 Mar 1

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Two dimensional electron gas
Oxygen vacancies
Oxygen
Crystalline materials
strontium titanium oxide
Growth temperature
Heterojunctions
Electron microscopes
Annealing
Scanning

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials

Cite this

Moon, Seon Young ; Moon, Cheon Woo ; Chang, Hye Jung ; Kim, Taemin ; Kang, Chong Yun ; Choi, Heon-Jin ; Kim, Jin Sang ; Baek, Seung Hyub ; Jang, Ho Won. / Comprehensive study on critical role of surface oxygen vacancies for 2DEG formation and annihilation in LaAlO3/SrTiO3 heterointerfaces. In: Electronic Materials Letters. 2016 ; Vol. 12, No. 2. pp. 243-250.
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abstract = "Here we report comprehensive study of 2DEG at a-LAO/STO interfaces in comparison with 2DEG at crystalline LaAlO3 (c-LAO)/STO interfaces. We observe that the oxygen deficient environment during the deposition of LAO overlayer is essentially required to create 2DEG at LAO/STO interface regardless of growth temperature from 25°C to 700°C, indicating that the oxygen-poor condition in the system is more important than the crystallinity of LAO layer. The critical thickness (2.6 nm) of 2DEG formation at a-LAO/STO heterostructure is thicker than (1.6 nm) that at c-LAO/STO. Upon ex-situ annealing at 300°C under 300 mTorr of oxygen pressure, 2DEG at a-LAO/STO interface is annihilated, while that in c-LAO/STO interface is still maintained. With combing these findings and scanning transmission electron microscope (STEM) analysis, we suggest that oxygen vacancies at the LAO surface is attributed to the origin of 2DEG formation at the LAO/STO and the crystallinity of the LAO overlayer plays a critical role in the annihilation of 2DEG at a-LAO/STO interface rather than in the formation of 2DEG. This work provides a framework to understand the importance of prohibiting the LAO surface from being oxidized for achieving thermally stable 2DEG at a-LAO/STO interface. [Figure not available: see fulltext.]",
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Comprehensive study on critical role of surface oxygen vacancies for 2DEG formation and annihilation in LaAlO3/SrTiO3 heterointerfaces. / Moon, Seon Young; Moon, Cheon Woo; Chang, Hye Jung; Kim, Taemin; Kang, Chong Yun; Choi, Heon-Jin; Kim, Jin Sang; Baek, Seung Hyub; Jang, Ho Won.

In: Electronic Materials Letters, Vol. 12, No. 2, 01.03.2016, p. 243-250.

Research output: Contribution to journalArticle

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T1 - Comprehensive study on critical role of surface oxygen vacancies for 2DEG formation and annihilation in LaAlO3/SrTiO3 heterointerfaces

AU - Moon, Seon Young

AU - Moon, Cheon Woo

AU - Chang, Hye Jung

AU - Kim, Taemin

AU - Kang, Chong Yun

AU - Choi, Heon-Jin

AU - Kim, Jin Sang

AU - Baek, Seung Hyub

AU - Jang, Ho Won

PY - 2016/3/1

Y1 - 2016/3/1

N2 - Here we report comprehensive study of 2DEG at a-LAO/STO interfaces in comparison with 2DEG at crystalline LaAlO3 (c-LAO)/STO interfaces. We observe that the oxygen deficient environment during the deposition of LAO overlayer is essentially required to create 2DEG at LAO/STO interface regardless of growth temperature from 25°C to 700°C, indicating that the oxygen-poor condition in the system is more important than the crystallinity of LAO layer. The critical thickness (2.6 nm) of 2DEG formation at a-LAO/STO heterostructure is thicker than (1.6 nm) that at c-LAO/STO. Upon ex-situ annealing at 300°C under 300 mTorr of oxygen pressure, 2DEG at a-LAO/STO interface is annihilated, while that in c-LAO/STO interface is still maintained. With combing these findings and scanning transmission electron microscope (STEM) analysis, we suggest that oxygen vacancies at the LAO surface is attributed to the origin of 2DEG formation at the LAO/STO and the crystallinity of the LAO overlayer plays a critical role in the annihilation of 2DEG at a-LAO/STO interface rather than in the formation of 2DEG. This work provides a framework to understand the importance of prohibiting the LAO surface from being oxidized for achieving thermally stable 2DEG at a-LAO/STO interface. [Figure not available: see fulltext.]

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