Visible electroluminescence from Eu:CaF2 layers grown by molecular beam epitaxy on p-Si (100)

Abstract

Visible electroluminescence (EL) is observed at room temperature by current injection into Eu:CaF2 layers containing 7.5 and 8.0 at. % Eu grown by molecular beam epitaxy on lightly doped (100) p-type silicon. The EL spectra are broad with peaks near 700 and 600 nm, respectively. Room temperature photoluminescence spectra for the same samples exhibited peaks near 420 nm, with higher doped samples showing a more pronounced long wavelength tail. Although both metal and indium–tin–oxide (ITO) contacts were successfully used for current injection, the best EL intensity stability was achieved with contacts made of a 100 Å thick Al layer covered by a 2500 Å thick ITO layer.

Graphite reinforced silane crosslinked high density polyethylene: The effect of filler loading on the thermal and mechanical properties

“…Halpin‐Tsai's approximation was also used to predict the modulus of the prepared composites. This model refers to the tensile behavior of composites that contain randomly oriented fibers and takes into consideration the reinforcement effect derived from the presence of rigid inclusions in the matrix without considering the filler‐filler and filler‐matrix interactions [ 64–69 ] . According to this model, the composites' modulus can be described by the following equation: where ξ = 2r and r the aspect ratio of the filler particle and η can be calculated from the following expression: …”

An effective medium model for the elastic moduli of fiber networks and nanocomposites

“…͑3͒, ␤ represents the critical exponent describing the growth of the percolation probability near the threshold, while the parameter ␣ controls the width of the transition and x͑L͒ is the dimensionless volume fraction in terms of the percolation threshold for rods of length L. Similar representations of the percolation probability, employing either the value for the exponent ␤ obtained from Monte Carlo simulations in three dimensions 26 ͑␤ = 0.47͒ or the mean-field value 19 ͑␤ =1͒, have been invoked in prior models 6,7 for the elastic properties of networks and composites. In Eq.…”

“…Upper and lower bounds on the moduli of composites are known, which are based solely on information regarding the volume fraction of each component and the properties of these components in their pure states. [6][7][8] A number of effective medium theories treat dispersions of spheroidal inclusions within an otherwise homogeneous matrix using the classical theory of elasticity. [6][7][8] A number of effective medium theories treat dispersions of spheroidal inclusions within an otherwise homogeneous matrix using the classical theory of elasticity.…”

“…[9][10][11][12][13][14] In the interpretation of acoustic signals, such aspherical inclusions have been employed to model voids or fluid-filled pores, i.e., to represent material more, rather than less, pliable than the embedding matrix. A recent micromechanical approach, 7 which embodies results from the theory of percolation, 19 is employed to evaluate the elastic coefficients which characterize the particle network considered in isolation. [15][16][17][18] The present work develops a unified mean-field model for the linear elastic moduli of macroscopically isotropic composites in which an elastomeric matrix is reinforced by elongated, rigid, filler particles.…”

Eu:CaF 2 layers on p-Si(100) grown using molecular beam epitaxy as materials for Si-based optoelectronics

“…% Eu. 8 In this article we report studies of morphological features of MBEgrown Eu:CaF 2 /Si͑100͒ layers using atomic force microscopy ͑AFM͒ and the EL emission spectra from EL devices fabricated with this material. Compatibility with standard silicon processing techniques makes this a promising materials system for integration of optical emitters with silicon circuitry.…”