Modified Failure Mechanism of Silicon through Excess Electrons and Holes
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https://doi.org/10.1007/s11837-020-04180-x Ó 2020 The Minerals, Metals & Materials Society
QUANTUM MATERIALS FOR ENERGY-EFFICIENT COMPUTING
Modified Failure Mechanism of Silicon through Excess Electrons and Holes YIDI SHEN1 and QI AN
1,2
1.—Department of Chemical and Materials Engineering, Reno, Reno, NV 89557, USA. 2.—e-mail: [email protected]
University
of
Nevada-
Electron and hole carriers are ubiquitous in quantum devices, while their effects on the mechanical properties of devices remain unclear. Here we use silicon (Si) as the prototype material and employ density functional theory to illustrate how electrons and holes influence its deformation and failure mechanism. First, we found that electrons and holes weaken the bonds in single-crystal Si, reducing the intrinsic yield strength. Then, the nanotwinned Si was deformed under ideal shear deformation to illustrate the interaction between carriers and microstructures. At neutral state, the nanotwinned Si experiences a structure recovery during shear deformation, whereas the bonds along twin boundaries (TBs) break with both excess electrons and holes. This arises from the injected carriers that are attracted by TBs, weakening the electrostatic interactions between bonded Si atoms near TBs. Our findings provide important information on the modified mechanical properties of Si with both excess electrons and holes.
INTRODUCTION Quantum materials, such as superconductors, graphene, and topologic insulators, exhibit such promising quantum properties as quantum fluctuations, quantum coherence, quantum entanglement, and electron–electron interactions.1–4 Particularly, silicon (Si) is one of the most promising quantum materials and has been widely used in quantum electronics, optoelectronics, and photovoltaic devices such as quantum computers, lightemitting diodes (LED), and solar cells.5–9 The tunable charges and spins in Si make it an excellent material for the new generation of microelectronic devices.8 Si also exhibits low spin–orbit coupling as well as the existence of isotopes without nuclear spin, making it suitable for hosting spin quantum bits (qubits) in quantum computing.9 In addition, Si is a promising candidate for the application of optoelectronics because of its capability to tune emissions through quantum confinement effects (QCEs).10 Furthermore, silicon-based quantum dots (QDs) have been applied in some newly developed solar cells such as tandem solar cells and hot carrier cells.7,11 Despite these excellent electronic and optical properties, Si suffers from brittle failure at low temperature, high pressure, and external
electric fields, which bottlenecks its wide engineering applications in quantum devices. Free carriers, including electrons and holes, play an important role in the mechanical properties of semiconductors and determine their mechanical stability under working conditions.12–14 Previous experimental studies indicated that the mechanical properties of semiconducting materials are sensitive to the photoinduced electron–hole pairs (EHPs
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