Structural and electrical properties of single crystalline SrZrO3 epitaxially grown on Ge (001)

Lim, Zheng Hui; Ahmadi-Majlan, Kamyar; Grimley, Everett D.; Du, Y.; Bowden, Mark E.; Moghadam, Reza; LeBeau, James M.; Chambers, Scott A.; Ngai, J. H.

doi:10.1063/1.5000142

Cited by 13 publications

(9 citation statements)

References 30 publications

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“…To increase the conduction band offsets, Jahangir‐Moghadam et al alloyed the B‐site Ti cations with Zr, forming the solid‐solution SrTi 1– z Zr x O 3 , or SZTO . This work was subsequently extended to x = 1, or SrZrO 3 , SZO . The addition of Zr to STO is known to increase the bandgap up to 5.6 eV for x = 1, which also raises the conduction band of the oxide above the conduction band of Ge, forming a barrier for electron transport.…”

Section: Materials and Functional Propertiesmentioning

confidence: 87%

Epitaxial Oxides on Semiconductors: From Fundamentals to New Devices

Kumah

Ngai

Kornblum

2019

Adv Funct Materials

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Functional oxides are an untapped resource for futuristic devices and functionalities. These functionalities can range from high temperature superconductivity to multiferroicity and novel catalytic schemes. The most prominent route for transforming these ideas from a single device in the lab to practical technologies is by integration with semiconductors. Moreover, coupling oxides with semiconductors can herald new and unexpected functionalities that exist in neither of the individual materials. Therefore, oxide epitaxy on semiconductors provides a materials platform for novel device technologies. As oxides and semiconductors exhibit properties that are complementary to one another, epitaxial heterostructures comprised of the two are uniquely poised to deliver rich functionalities. This review discusses recent advancements in the growth of epitaxial oxides on semiconductors, and the electronic and physical structure of their interfaces. Leaning on these fundamentals and practicalities, the material behavior and functionality of semiconductor-oxide heterostructures is discussed, and their potential as device building blocks is highlighted. The culmination of this discussion is a review of recent advances in the development of prototype devices based on semiconductor-oxide heterostructures, in areas ranging from silicon photonics to photocatalysis. This overview is intended to stimulate ideas for new concepts of functional devices and lay the groundwork for their realization.

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Section: Materials and Functional Propertiesmentioning

confidence: 87%

Epitaxial Oxides on Semiconductors: From Fundamentals to New Devices

Kumah

Ngai

Kornblum

2019

Adv Funct Materials

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“…In particular, the electronic properties have been of long-standing importance in gate dielectric technology and, more recently, are of potential interest in clean energy applications such as photoelectrochemical water splitting [1]. The prototypical crystalline oxide for fundamental studies of oxide/semiconductor heteroepitaxy is SrTiO3 (STO) [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. STO is a wide gap semiconductor (Eg = 3.25 eV) that is readily doped n-type by LaSr, NbTi and O vacancies (VO).…”

Section: Introductionmentioning

confidence: 99%

Layer-resolved band bending at the n−SrTiO3(001)/p−Ge(001) interface

Sushko

Spurgeon

et al. 2018

Phys. Rev. Materials

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The electronic properties of epitaxial heterojunctions consisting of the prototypical perovskite oxide semiconductor,n-SrTiO3 and the high-mobility Group IV semiconductor p-Ge have been investigated. Hard x-ray photoelectron spectroscopy with a new method of analysis has been used to determine band alignment while at the same time quantifying a large built-in potential found to be present within the Ge.Accordingly, the built-in potential within the Ge has been mapped in a layer-resolved fashion. Electron transfer from donors in the n-SrTiO3 to the p-Ge creates a space-charge region in the Ge resulting in downward band bending which spans most of the Ge gap. This strong downward band bending facilitates visible-light, photo-generated electron transfer from Ge to STO, favorable to drive the hydrogen evolution reaction associated with water splitting. Ti 2p and Sr 3d core-level line shapes reveal that the STO bands are flat despite the space-charge layer therein. Inclusion of the effect of Ge band bending on band alignment is significant, amounting to a ~0.4 eV reduction in valence band offset compared to the value resulting from using spectra averaged over all layers. Density functional theory allows candidate interface structural models deduced from scanning transmission electron microscopy images to be simulated and structurally optimized. These structures are used to generate multi-slice simulations that reproduce the experimental images quite well. The calculated band offsets for these structures are in good agreement with experiment.

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“…1,2 McKee first reported epitaxial growth of SrTiO 3 (STO) on silicon in 1998. 3 The study of crystalline perovskites on semiconductors has been widely expanded subsequently for device applications, [4][5][6][7][8][9][10][11][12][13] including the use of crystalline perovskites as a high-k gate oxide for field-effect transistor device applications. 14 In the past several decades, the goals of faster computing speed and lower power consumption have led to eversmaller transistor feature sizes and ever-thinner gate oxide.…”

Section: Introductionmentioning

confidence: 99%

“…10,13,22,23 Several groups have studied growth of crystalline SZO by molecular beam epitaxy (MBE) or pulsed laser deposition (PLD). 13,22,24 Herein, we report ALD growth of crystalline SZO and approaches to reduce the D it through steps taken prior to ALD and by annealing SZO/ Ge in a flux of atomic deuterium. Comparison of various Group 4 B-site cations in ALD-grown crystalline ABO 3 perovskites shows Zr to perform the best among Ti, Zr, and Hf in terms of leakage current density and D it .…”

Section: Introductionmentioning

confidence: 99%

Crystalline SrZrO3 deposition on Ge (001) by atomic layer deposition for high-k dielectric applications

Chen

et al. 2018

Journal of Applied Physics

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Heteroepitaxial growth of crystalline SrZrO3 (SZO) on Ge (001) by atomic layer deposition is reported. Ge (001) surfaces are pretreated with 0.5-monolayers (ML) of Ba and an amorphous ∼3-nm SZO layer is grown from strontium bis(triisopropylcyclopentadienyl), tetrakis (dimethylamido) zirconium, and water at 225 °C. This ∼3-nm layer crystallizes at 590 °C and subsequent SZO growth at 225 °C leads to crystalline films that do not require further annealing. The film properties are investigated using X-ray photoelectron spectroscopy, x-ray diffraction, aberration-corrected electron microscopy, and capacitance-voltage measurements of metal-oxide semiconductor capacitor structures. Capacitance-voltage measurements of the SrZrO3/Ge heterojunctions reveal a dielectric constant of 30 for SrZrO3 and a leakage current density of 2.1 × 10−8 A/cm2 at 1 MV/cm with an equivalent oxide thickness of 0.8 nm. Oxygen plasma pretreatment of Ge (001), Zintl layer formation with 0.5 ML Ba, and atomic deuterium post-growth treatment were explored to lower interface trap density (Dit) and achieved a Dit of 8.56 × 1011 cm−2 eV−1.

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Structural and electrical properties of single crystalline SrZrO3 epitaxially grown on Ge (001)

Cited by 13 publications

References 30 publications

Epitaxial Oxides on Semiconductors: From Fundamentals to New Devices

Epitaxial Oxides on Semiconductors: From Fundamentals to New Devices

Layer-resolved band bending at the n−SrTiO3(001)/p−Ge(001) interface

Crystalline SrZrO3 deposition on Ge (001) by atomic layer deposition for high-k dielectric applications

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