Epitaxial thin film transfer for flexible devices from reusable substrates

Jovanovic, Stephen M.; Devenyi, Gabriel A.; Kuyanov, P; Carvalho, Jessica L.; Meinander, Kristoffer; LaPierre, Ray; Preston, John S.

doi:10.1088/2053-1591/aaf264

Cited by 4 publications

(4 citation statements)

References 31 publications

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“…The expected in‐plane lattice mismatch of the α‐ Al 2 O 3 (0001)/CdTe (111) system is 3.7%, as seen from the lattice spacings in Figure 1a; however, CdTe films are observed to be strain relaxed without the density of dislocation networks that would be expected from the misfit strain (Figure S3, Supporting Information). The demonstrated ease of thin film transfer seen in Figure 1d, which has been utilized prior to fabricate a simple rectifying heterostructure, [ 16 ] an observed preferential etching of the interface during lift‐out preparation (Figure S4, Supporting Information), and a lack of residual heteroepitaxial strain in the film, as measured by high resolution XRD and observed in STEM images (Figures S5 and S6, Supporting Information), are all consistent with weak bonding at the interface. Sapphire substrates, post film transfer, have also been shown to support multiple film regrowth without significant quality degradation.…”

Section: Figurementioning

confidence: 99%

“…Sapphire substrates, post film transfer, have also been shown to support multiple film regrowth without significant quality degradation. [ 16 ]…”

Section: Figurementioning

confidence: 99%

“…Sapphire substrates, post film transfer, have also been shown to support multiple film regrowth without significant quality degradation. [16] This interface between the CdTe film and the α-Al 2 O 3 substrate was probed directly in cross-sectional samples prepared by focus ion beam (FIB) for STEM. Figure 2a reveals the CdTe (111) film epitaxially aligned in-and out-of-plane, as consistent with the XRD, but incommensurate to the sapphire substrate spacing.…”

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Spontaneous Relaxation of Heteroepitaxial Thin Films by van der Waals‐Like Bonding on Te‐Terminated Sapphire Substrates

Jovanovic

El‐Sherif

Bassim

et al. 2020

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Heteroepitaxy of thin film materials is a fundamental industrial process for the fabrication of high-quality electronic and electrooptic devices. Conventionally, strong bonding of adatoms on a substrate leads to a coherent thin film below a critical thickness, where the thin film grows strained from its relaxed lattice spacing. Above this critical thickness strain is relieved by defect generation in the thin film. Commercial development of heteroepitaxial technologies is limited by both the availability and cost of lattice-matched substrates. This lattice matching requirement is diminished for van der Waals (vdW) heteroepitaxial systems due to weak interlayer

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Section: Figurementioning

confidence: 99%

“…Sapphire substrates, post film transfer, have also been shown to support multiple film regrowth without significant quality degradation. [ 16 ]…”

Section: Figurementioning

confidence: 99%

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confidence: 99%

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Spontaneous Relaxation of Heteroepitaxial Thin Films by van der Waals‐Like Bonding on Te‐Terminated Sapphire Substrates

Jovanovic

El‐Sherif

Bassim

et al. 2020

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“…For thermomechanical delamination, a stressor and handle are applied to a film stack grown under standard conditions and a negative temperature gradient is applied, causing the stressor to contract until spontaneous cleavage occurs. For sx material (e.g., Si, [55,56] III-Vs, [57] CdTe), [58] it is common to initiate a crack prior to the final anneal step such that delamination will occur during the cooldown. Other studies have thermomechanically cleaved sx films without the preinitiated crack, by applying a much larger thermal strain, e.g., by dipping in LN 2 .…”

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Thermomechanical Cleave of Polycrystalline CdTe Solar Cells and its Applications: A Review

2023

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One of the primary research challenges for cadmium telluride (CdTe) solar cells is addressing its open‐circuit voltage (VOC) deficit. While theoretical studies and single crystal work show VOC > 1 V is possible, devices remain stubbornly low at ≈800–900 mV. As absorber opto‐electronic properties (e.g., hole density, carrier lifetime) are improved, device modeling suggests that interfaces become limiting. Because CdTe‐based devices are typically grown in the superstrate configuration, the back interface is relatively accessible for manipulation and study, while the front interface (i.e., the heterojunction region) is buried under microns of material and inaccessible. NREL has developed a novel technique to thermomechanically cleave polycrystalline CdTe device stacks directly at the front interface, enabling characterization and controlled manipulation of this important region. Herein, recent work, primarily from NREL, will be reviewed, including considerations for achieving successful delamination; key scientific discoveries about the front interface that have been enabled by this technique; and practical applications, such as flexible, low‐cost solar with high power‐to‐weight ratio.

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Electron Microscopy and Interface Plasmons Characterization of Cadmium Telluride Thin Film Grown Incommensurately with Weak Bonding on Sapphire

et al. 2020

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Cadmium Telluride (CdTe) thin films are important materials for optoelectronic and radiation detection applications. Fabrication of CdTe films has been studied using a variety of substrates via heteroepitaxial growth. As a result of the lattice mismatch strain, the CdTe films usually contain threading and misfit dislocations that limit device performance. Recently, a remote epitaxy technique [1] was demonstrated for homoepitaxial systems by transferring a graphene sheet onto the substrate before deposition of the film. Applied to a heteroepitaxial system, this type of compliant interface would allow for the accommodation of misfit strain due to weakened interfacial bonding. In this current work, a similar compliant interface is created by direct growth [2], without the use of pre-transferred graphene, and instead by the self-assembly of a Tellurium (Te) monolayer at the interface [3]. Utilizing pulsed laser deposition (PLD), high-quality epitaxial CdTe films can be grown on sapphire and then transferred from their substrate to be freestanding leaving the substrate for subsequent growths.

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Epitaxial thin film transfer for flexible devices from reusable substrates

Cited by 4 publications

References 31 publications

Spontaneous Relaxation of Heteroepitaxial Thin Films by van der Waals‐Like Bonding on Te‐Terminated Sapphire Substrates

Spontaneous Relaxation of Heteroepitaxial Thin Films by van der Waals‐Like Bonding on Te‐Terminated Sapphire Substrates

Thermomechanical Cleave of Polycrystalline CdTe Solar Cells and its Applications: A Review

Electron Microscopy and Interface Plasmons Characterization of Cadmium Telluride Thin Film Grown Incommensurately with Weak Bonding on Sapphire

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