Diffusons, Locons, Propagons: Character of Atomic Vibrations in Amorphous Si
نویسندگان
چکیده
Numerical studies of amorphous silicon show that the lowest 4% of vibrational modes are plane-wave like (“propagons”) and the highest 3% of modes are localized (“locons”). The rest are neither plane-wave like nor localized. We call them “diffusons.” Since diffusons are by far the most numerous, we try to characterize them by calculating such properties as wavevector and polarization (which seem not to be useful), “phase quotient” (a measure of the change of vibrational phase on between first neighbor atoms), spatial polarization memory, and diffusivity. Localized states are characterized by finding decay lengths, inverse participation ratios, and coordination numbers of the atoms participating.
منابع مشابه
Thermal transport in amorphous materials: a review
Thermal transport plays a crucial role in performance and reliability of semiconductor electronic devices, where heat is mainly carried by phonons. Phonon transport in crystalline semiconductor materials, such as Si, Ge, GaAs, GaN, etc, has been extensively studied over the past two decades. In fact, study of phonon physics in crystalline semiconductor materials in both bulk and nanostructure f...
متن کاملNon-negligible Contributions to Thermal Conductivity From Localized Modes in Amorphous Silica
Thermal conductivity is an important property for almost all applications involving heat transfer, ranging from energy and microelectronics to food processing and textiles. The theory and modeling of crystalline materials is in some sense a solved problem, where one can now calculate the thermal conductivity of any crystalline line compound from first principles [1,2] using expressions based on...
متن کاملThe structure of electronic states in amorphous silicon.
We illustrate the structure and dynamics of electron states in amorphous Si. The nature of the states near the gap at zero temperature is discussed and especially the way the structure of the states changes for energies ranging from midgap into either band tail (Anderson transition). We then study the effect of lattice vibrations on the eigenstates, and find that electronic states near the opti...
متن کاملUltrafast vibrational dynamics and stability of deuterated amorphous silicon.
Infrared four-wave mixing experiments performed upon deuterated amorphous silicon layers (a-Si:D) reveal profound differences in the dynamics of Si-D stretch vibrations compared to those of analogous Si-H vibrational modes in hydrogenated amorphous silicon (a-Si:H). Remarkably, transient-grating measurements of the population decay rate of the Si-D vibrations show single-exponential decay direc...
متن کاملNon-negligible Contributions to Thermal Conductivity From Localized Modes in Amorphous Silicon Dioxide
Thermal conductivity is important for almost all applications involving heat transfer. The theory and modeling of crystalline materials is in some sense a solved problem, where one can now calculate their thermal conductivity from first principles using expressions based on the phonon gas model (PGM). However, modeling of amorphous materials still has many open questions, because the PGM itself...
متن کامل