Tensile strain mapping in flat germanium membranes

Rhead, Stephen; Halpin, John E.; Shah, V. A.; Myronov, Maksym; Patchett, David; Allred, Phil; Kachkanov, V.; Dolbnya, Igor P.; Reparaz, J. S.; Wilson, Neil R.; Torres, C. M. Sotomayor; Leadley, D. R.

doi:10.1063/1.4874836

Cited by 12 publications

(7 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…High-resolution XRD provides a very sensitive technique for measuring relative changes in lattice constants and therefore strain in crystalline materials. While standard XRD tools employ relatively large beams (typically a few 100 μm), focused nanoprobes that have recently become available at advanced synchrotron sources can achieve spot sizes smaller than 100 nm. , These systems operated in scanning mode combine high angular resolution in reciprocal space with high spatial resolution in real space and therefore are ideally suited to study lateral strain profiles in crystalline samples. ,,− In the present study, these capabilities are particularly significant as a way to enable mapping the strain variations with position on the NM plane around the overlying pillars. At the same time, the determination of absolute strain values with these tools is less accurate without an external calibration reference.…”

Section: Resultsmentioning

confidence: 99%

Strain-Induced Lateral Heterostructures in Patterned Semiconductor Nanomembranes for Micro- and Optoelectronics

Gök

Wang

Scott

et al. 2021

ACS Appl. Nano Mater.

View full text Add to dashboard Cite

The ability to tailor the energy band lineup of semiconductor materials plays a key role in the development of many electronic and optoelectronic devices and normally relies on heteroepitaxy. Here, we report a different method, based on strain engineering, for the controlled introduction of variations in bandgap energy with lateral position in thin films. External stress is applied on Ge nanomembranes stacked with an array of amorphous-Si pillars in order to create a non-uniform strain (and therefore bandgap energy) distribution commensurate with the sample thickness variations. The resulting strain profiles are mapped using Bragg diffraction with a hard X-ray probe featuring nanoscale spatial resolution. Compared with traditional heterostructures grown by epitaxial techniques, these strain-engineered samples involve a single chemical composition and are not limited in the choice of compatible materials by any restriction imposed by latticematching requirements. Furthermore, their energy band lineups can be patterned in nearly arbitrary shapes using nanolithography to control the thickness profile and can be tuned actively by varying the applied stress. As a result, these structures are attractive for a wide range of device applications (including lasers, LEDs, solar cells, and thermoelectrics) that require complex heterostructure lineups with multiple bandgap energies.

show abstract

Section: Resultsmentioning

confidence: 99%

Strain-Induced Lateral Heterostructures in Patterned Semiconductor Nanomembranes for Micro- and Optoelectronics

Gök

Wang

Scott

et al. 2021

ACS Appl. Nano Mater.

View full text Add to dashboard Cite

show abstract

“…Further modification of the membranes by lithographic patterning [22] or strain engineering [23] leads to additional functionalities such as photonic devices and flexible electronics. Recent work has extended the use of these techniques to other materials, such as germanium, silicon-germanium multilayers, and silicon-silicon dioxide hetero-structures [24][25][26] further expanding the scope of potential applications.…”

Section: Discussionmentioning

confidence: 99%

Fabrication of Single Crystal Silicon Nanomembranes

Gopalakrishnan¹

2018

RDMS

View full text Add to dashboard Cite

Silicon nanomembranes are thin, free standing sheets of single or poly-crystalline silicon, typically less than a micrometer thick, with lateral dimensions exceeding the thickness by several orders of magnitude. Nanomembranes have applications in flexible electronics, pressure sensing, photonic and phononic devices, sample mounts for microscopy, windows and beam splitters for optical and x-ray scattering measurements, and as a model system to perform fundamental investigations of nanoscale phenomena. This review covers fabrication processes for creating single crystal nanomembranes from a silicon-on-insulator (SOI) wafer as the starting material.

show abstract

“…The second sample is a cubic silicon carbide (3C-SiC) suspended thin film with a Si substrate, which has the opposite thermal effect to Ge as the sample is cooled from the growth temperature because 3C-SiC has a smaller CTE than Si, with a turning point in measurements of the CTE at a temperature of around 220 • C. The thermal expansion coefficients of thin film and substrate materials [13]. Both materials are single crystalline and cubic, 3C-SiC(100) and Ge(100), as confirmed by X-ray diffraction [31]- [33], and can therefore be taken to be isotropic. Mode mixing of modes has been shown to occur on a square membrane, for example modes 2:3 and 3:2 occurring at the same frequency, confirming the isotropic nature of the vibration [6].…”

Section: Residual Stress and Temperaturementioning

confidence: 99%

Ultrasonic Inspection and Self-Healing of Ge and 3C-SiC Semiconductor Membranes

Zhou

Colston

Myronov

et al. 2020

J. Microelectromech. Syst.

Self Cite

View full text Add to dashboard Cite

Knowledge of the mechanical properties and stability of thin film structures is important for device operation. Potential failures related to crack initiation and growth must be identified early, to enable healing through e.g. annealing. Here, three square suspended membranes, formed from a thin layer of cubic silicon carbide (3C-SiC) or germanium (Ge) on a silicon substrate, were characterised by their response to ultrasonic excitation. The resonant frequencies and mode shapes were measured during thermal cycling over a temperature range of 20-100 • C. The influence of temperature on the stress was explored by comparison with predictions from a model of thermal expansion of the combined membrane and substrate. For an ideal, non-cracked sample the stress and Q-factor behaved as predicted. In contrast, for a 3C-SiC and a Ge membrane that had undergone vibration and thermal cycling to simulate extended use, measurements of the stress and Q-factor showed the presence of damage, with the 3C-SiC membrane subsequently breaking. However, the damaged Ge sample showed an improvement to the resonant behaviour on subsequent heating. Scanning electron microscopy showed that this was due to a self-healing of sub-micrometer cracks, caused by expansion of the germanium layer to form bridges over the cracked regions, with the effect also observable in the ultrasonic inspection. [2020-0017] Index Terms-Laser ultrasound, vibration, microelectromechanical systems (MEMS), thin films. I. INTRODUCTION S OLID thin films are used in a wide variety of engineering systems, including development of micro-electromechanical systems (MEMS) and nano-electro-mechanical systems (NEMS) [1]-[4]. The suspended square thin film is a simple MEMS structure and can be used in pressure sensors, or as a platform for integrating devices for applications such as near-infrared photo-detectors, flow sensors, photonic modulators, lasers, and enhancing silicon light emission via carrier injection [5]-[10]. The use of tensile strained membranes, such as Germanium (Ge) on Silicon (Si), can change the electronic or optoelectronic properties by reducing the energy band gap [11], [12]. However, the residual stress in thin films, especially within a multilayer structure, is temperature dependent. Changes in temperature can induce mechanical Manuscript

show abstract

Tensile strain mapping in flat germanium membranes

Cited by 12 publications

References 38 publications

Strain-Induced Lateral Heterostructures in Patterned Semiconductor Nanomembranes for Micro- and Optoelectronics

Strain-Induced Lateral Heterostructures in Patterned Semiconductor Nanomembranes for Micro- and Optoelectronics

Fabrication of Single Crystal Silicon Nanomembranes

Ultrasonic Inspection and Self-Healing of Ge and 3C-SiC Semiconductor Membranes

Contact Info

Product

Resources

About