A Chemical Route to Monolithic Integration of Crystalline Oxides on Semiconductors. Issue 8 (2nd May 2014)

• Record Type: Journal Article
• Authors: McDaniel, Martin D.; Ngo, Thong Q.; Posadas, Agham; Hu, Chengqing; Lu, Sirong; Smith, David J.; Yu, Edward T.; Demkov, Alexander A.; Ekerdt, John G.
• Is Part Of: Advanced materials interfaces. Volume 1:Issue 8(2014)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2014-05-02
• Subjects: Materials science -- Periodicals; 620.11
• DOI: 10.1002/admi.201400081
• Languages: English
• ISSNs: 2196-7350

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>This work demonstrates the growth of crystalline SrTiO<sub>3</sub> (STO) directly on germanium via a chemical method. After thermal deoxidation, the Ge substrate is transferred <italic>in vacuo</italic> 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 (<italic>k</italic> ≈ 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<sub>1‐x­</sub>Al<sub>x</sub>O<sub>3‐δ</sub>) 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.</p> </abstract>