A Chemical Route to Monolithic Integration of Crystalline Oxides on Semiconductors

Martin D. McDaniel, Thong Q. Ngo, Agham Posadas, Chengqing Hu, Sirong Lu, David Smith, Edward T. Yu, Alexander A. Demkov, John G. Ekerdt

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

This work demonstrates the growth of crystalline SrTiO<inf>3</inf> (STO) directly on germanium via a chemical method. After thermal deoxidation, the Ge substrate is transferred in vacuo to the deposition chamber where a thin film of STO (2 nm) is deposited by atomic layer deposition (ALD) at 225°C. Following post-deposition annealing at 650°C for 5 min, the STO film becomes crystalline with epitaxial registry to the underlying Ge (001) substrate. Thicker STO films (up to 15 nm) are then grown on the crystalline STO seed layer. The crystalline structure and orientation are confirmed via reflection high-energy electron diffraction, X-ray diffraction, and transmission electron microscopy. Electrical measurements of a 15-nm thick epitaxial STO film on Ge show a large dielectric constant (k ≈ 90), but relatively high leakage current of ≈10 A/cm<sup>2</sup> for an applied field of 0.7 MV/cm. To suppress the leakage current, an aluminum precursor is cycled during ALD growth to grow crystalline Al-doped STO (SrTi<inf>1-x</inf>Al<inf>x</inf>O<inf>3-δ</inf>) films. With sufficient Al doping (≈13%), the leakage current decreases by two orders of magnitude for an 8-nm thick film. The current work demonstrates the potential of ALD-grown crystalline oxides to be explored for advanced electronic applications, including high-mobility Ge-based transistors. Crystalline SrTiO<inf>3</inf> is grown directly on Ge (001) via a chemical deposition method. This growth technique has wide reaching potential for the monolithic integration of many functional perovskite oxides with semiconductors. The current work exhibits the promise for ALD-grown crystalline oxides for advanced electronic applications, especially high-mobility Ge-based transistors.

Original languageEnglish (US)
Article number1400081
JournalAdvanced Materials Interfaces
Volume1
Issue number8
DOIs
StatePublished - Nov 1 2014

Fingerprint

Semiconductor materials
Crystalline materials
Oxides
Atomic layer deposition
Thick films
Leakage currents
Transistors
Reflection high energy electron diffraction
Epitaxial films
Substrates
Germanium
Crystal orientation
Perovskite
Seed
Permittivity
Doping (additives)
Annealing
Transmission electron microscopy
Aluminum
X ray diffraction

Keywords

  • atomic layer deposition
  • crystalline oxides
  • epitaxy
  • germanium
  • high-k dielectrics

ASJC Scopus subject areas

  • Mechanical Engineering
  • Mechanics of Materials

Cite this

A Chemical Route to Monolithic Integration of Crystalline Oxides on Semiconductors. / McDaniel, Martin D.; Ngo, Thong Q.; Posadas, Agham; Hu, Chengqing; Lu, Sirong; Smith, David; Yu, Edward T.; Demkov, Alexander A.; Ekerdt, John G.

In: Advanced Materials Interfaces, Vol. 1, No. 8, 1400081, 01.11.2014.

Research output: Contribution to journalArticle

McDaniel, MD, Ngo, TQ, Posadas, A, Hu, C, Lu, S, Smith, D, Yu, ET, Demkov, AA & Ekerdt, JG 2014, 'A Chemical Route to Monolithic Integration of Crystalline Oxides on Semiconductors', Advanced Materials Interfaces, vol. 1, no. 8, 1400081. https://doi.org/10.1002/admi.201400081
McDaniel, Martin D. ; Ngo, Thong Q. ; Posadas, Agham ; Hu, Chengqing ; Lu, Sirong ; Smith, David ; Yu, Edward T. ; Demkov, Alexander A. ; Ekerdt, John G. / A Chemical Route to Monolithic Integration of Crystalline Oxides on Semiconductors. In: Advanced Materials Interfaces. 2014 ; Vol. 1, No. 8.
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abstract = "This work demonstrates the growth of crystalline SrTiO3 (STO) directly on germanium via a chemical method. After thermal deoxidation, the Ge substrate is transferred in vacuo to the deposition chamber where a thin film of STO (2 nm) is deposited by atomic layer deposition (ALD) at 225°C. Following post-deposition annealing at 650°C for 5 min, the STO film becomes crystalline with epitaxial registry to the underlying Ge (001) substrate. Thicker STO films (up to 15 nm) are then grown on the crystalline STO seed layer. The crystalline structure and orientation are confirmed via reflection high-energy electron diffraction, X-ray diffraction, and transmission electron microscopy. Electrical measurements of a 15-nm thick epitaxial STO film on Ge show a large dielectric constant (k ≈ 90), but relatively high leakage current of ≈10 A/cm2 for an applied field of 0.7 MV/cm. To suppress the leakage current, an aluminum precursor is cycled during ALD growth to grow crystalline Al-doped STO (SrTi1-xAlxO3-δ) films. With sufficient Al doping (≈13{\%}), the leakage current decreases by two orders of magnitude for an 8-nm thick film. The current work demonstrates the potential of ALD-grown crystalline oxides to be explored for advanced electronic applications, including high-mobility Ge-based transistors. Crystalline SrTiO3 is grown directly on Ge (001) via a chemical deposition method. This growth technique has wide reaching potential for the monolithic integration of many functional perovskite oxides with semiconductors. The current work exhibits the promise for ALD-grown crystalline oxides for advanced electronic applications, especially high-mobility Ge-based transistors.",
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AB - This work demonstrates the growth of crystalline SrTiO3 (STO) directly on germanium via a chemical method. After thermal deoxidation, the Ge substrate is transferred in vacuo to the deposition chamber where a thin film of STO (2 nm) is deposited by atomic layer deposition (ALD) at 225°C. Following post-deposition annealing at 650°C for 5 min, the STO film becomes crystalline with epitaxial registry to the underlying Ge (001) substrate. Thicker STO films (up to 15 nm) are then grown on the crystalline STO seed layer. The crystalline structure and orientation are confirmed via reflection high-energy electron diffraction, X-ray diffraction, and transmission electron microscopy. Electrical measurements of a 15-nm thick epitaxial STO film on Ge show a large dielectric constant (k ≈ 90), but relatively high leakage current of ≈10 A/cm2 for an applied field of 0.7 MV/cm. To suppress the leakage current, an aluminum precursor is cycled during ALD growth to grow crystalline Al-doped STO (SrTi1-xAlxO3-δ) films. With sufficient Al doping (≈13%), the leakage current decreases by two orders of magnitude for an 8-nm thick film. The current work demonstrates the potential of ALD-grown crystalline oxides to be explored for advanced electronic applications, including high-mobility Ge-based transistors. Crystalline SrTiO3 is grown directly on Ge (001) via a chemical deposition method. This growth technique has wide reaching potential for the monolithic integration of many functional perovskite oxides with semiconductors. The current work exhibits the promise for ALD-grown crystalline oxides for advanced electronic applications, especially high-mobility Ge-based transistors.

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KW - high-k dielectrics

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