Giant shift upon strain on the fluorescence spectrum of VNNB color centers in h-BN

We study the effect of strain on the physical properties of the nitrogen antisite-vacancy pair in hexagonal boron nitride (h-BN), a color center that may be employed as a quantum bit in a two-dimensional material. With group theory and ab initio analysis we show that strong electron–phonon coupling plays a key role in the optical activation of this color center. We find a giant shift on the zero-phonon-line (ZPL) emission of the nitrogen antisite-vacancy pair defect upon applying strain that is typical of h-BN samples. Our results provide a plausible explanation for the experimental observation of quantum emitters with similar optical properties but widely scattered ZPL wavelengths and the experimentally observed dependence of the ZPL on the strain.

Electrical Trimming Characteristics of Polysilicon Nanofilms with Different Doping Concentrations and Deposition Temperatures

Polysilicon nanofilm (PSNF) can provide a large gauge factor and good temperature stability, which promotes their application in piezoresistive sensing devices. Electrical trimming is necessary to further improve the stability and matching of piezoresistive resistors after sensor fabrication. The advantages of PSNF are realized by first preparing PSNF samples with different doping concentrations and deposition temperatures. By applying an incremental DC current that is higher than the threshold current of the PSNF resistors, the PSNF resistors are trimmed and the resistance changes are measured. The results of electrical trimming show that the threshold current, trimming rate, and trimming error are related to the doping concentration and deposition temperature. According to tunneling piezoresistive theory and the interstitial-vacancy pair model, the experimental results are expounded. These results are useful for the design and fabrication of PSNF piezoresistive sensors.

Uncovering the microscopic mechanism of incorporating Mn2+ ions into CsPbCl3 crystal lattice

Based on a four-precursor synthetic strategy and DFT calculation, we verify that excessive chloride ion concentration benefits the formation of bond [Pb⋯Cl] vacancy pair as well as the subsequent incorporation of [Mn⋯Cl] ion pair.

Computational Analysis of Coupled Anisotropic Chemical Expansion in Li2-XMnO3-δ

ABSTRACTDuring the activation and charge process, vacancies are generated in the Li2MnO3 component in lithium-rich layered cathode materials. The chemical expansion coefficient tensor associated with oxygen vacancies, lithium vacancies and a Li-O vacancy pair were calculated for Li2-xMnO3-δ. The chemical expansion coefficient was larger for oxygen vacancies than for lithium vacancies in most directions. Additionally, the chemical expansion coefficient for a Li-O vacancy pair was shown to not be a linear sum of the chemical expansion coefficients of the two vacancy types, suggesting that the oxygen vacancies and lithium vacancies in Li2-XMnO3-δ exhibit a coupling effect.

Theoretical Investigation of the Single Photon Emitter Carbon Antisite-Vacancy Pair in 4H-SiC

Well addressable and controllable point defects in device friendly semiconductors are desired for quantum computational and quantum informational processes. Recently, such defect, an ultra-bright single photon emitter, the antisite carbon carbon vacancy pair, was experimentally investigated in 4H-SiC. In our theoretical work, based onab initiocalculation and group theory analysis, we provide a deeper understanding of the features of the electronic structures and the luminescence process of this defect.

Formulation of Impurity-Vacancy Pair Formation Energy in Fast Diffusion

In fast diffusion, the impurity diffusion coefficient is much greater than the self-diffusion coefficient. The pair mechanism is here considered to explain fast diffusion. Formulations for the formation of the pair are based upon pseudopotential theory.