scholarly journals Band Structure and Effective Masses of Zn1-xMgxO

2012 ◽  
Vol 1494 ◽  
pp. 57-63 ◽  
Author(s):  
Christian Franz ◽  
Marcel Giar ◽  
Markus Heinemann ◽  
Michael Czerner ◽  
Christian Heiliger
Keyword(s):  
Band Structure ◽  
Spectral Density ◽  
Ab Initio ◽  
Mass Model ◽  
Potential Approximation ◽  
Effective Electron ◽  
Effective Masses ◽  
Valence Bands ◽  
Effective Mass Model ◽  
Finite Concentrations

ABSTRACTWe analyze the influence of the Mg concentration on several important properties of the band structure of Zn1-xMgxO alloys in wurtzite structure using ab initio calculations. For this purpose, the band structure for finite concentrations is defined in terms of the Bloch spectral density, which can be calculated within the coherent potential approximation. We investigate the concentration dependence of the band gap and the crystal-field splitting of the valence bands. The effective electron and hole masses are determined by extending the effective mass model to finite concentrations. We compare our results with experimental results and other calculations.

scholarly journals Ab initio calculations of conduction band effective mass parameters of thermoelectric $${\hbox {Mg}}_{2} {\hbox {X}}_{1{-}x} {\hbox {Y}}_x$$ (X, Y = Si, Ge, Sn) alloys

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Juan M. Guerra ◽  
Carsten Mahr ◽  
Marcel Giar ◽  
Michael Czerner ◽  
Christian Heiliger
Keyword(s):  
Ab Initio ◽  
Effective Mass ◽  
Theoretical Data ◽  
Miscibility Gap ◽  
Transport Parameters ◽  
Potential Approximation ◽  
Effective Masses ◽  
Mass Approximation ◽  
Conduction Bands ◽  
Formation Energies

Abstract Since there are still research interests in the physical properties of quasi-binary thermoelectric $${\hbox {Mg}}_{2} {\hbox {X}}_{1-x}{\hbox {Y}}_{x}$$ Mg 2 X 1 - x Y x alloys, with X, Y = Si, Ge, Sn, we present an ab initio analysis that yields the relative formation energy and effective masses of the conduction bands, in the whole compositional range x. We base our calculations on the full-relativistic Korringa, Kohn and Rostocker (KKR) Green’s functions formalism within the coherent potential approximation (CPA). Formation energies, measured relative to the end $${\hbox {Mg}}_{2} \hbox {X}$$ Mg 2 X compounds, show no excess energy for the $${\hbox {Mg}}_{2} \hbox {Si} {-} {\hbox {Mg}}_{2} \hbox {Ge}$$ Mg 2 Si - Mg 2 Ge substitution thus indicating a complete solubility. In contrast, concave and asymmetric formation energies for intermediate compositions in the $${\hbox {Mg}}_{2} \hbox {X} {-} {\hbox {Mg}}_{2} \hbox {Sn}$$ Mg 2 X - Mg 2 Sn alloys manifest a miscibility gap. With this basis, we compute and discuss the crossing of the conduction bands observed in n-type $${\hbox {Mg}}_{2} {\hbox {X}}_{1-x} {\hbox {Sn}}_x$$ Mg 2 X 1 - x Sn x materials. We present direction- and band-dependent effective masses using a generalized single parabolic band effective mass approximation to discuss anisotropic effects, to interpret available experimental and theoretical data, and to predict intermediate and not yet published transport parameters on these alloys.

scholarly journals The Highly Uniform Photoresponsivity from Visible to Near IR Light in Sb2Te3 Flakes

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1535
Author(s):  
Shiu-Ming Huang ◽  
Jai-Lung Hung ◽  
Mitch Chou ◽  
Chi-Yang Chen ◽  
Fang-Chen Liu ◽  
...  
Keyword(s):  
Band Structure ◽  
Energy Difference ◽  
Experimental Result ◽  
Light Illumination ◽  
Near Ir ◽  
State Band ◽  
Valence Bands ◽  
Low Dimensional ◽  
Low Dimensional Materials ◽  
Ir Light

Broadband photosensors have been widely studied in various kinds of materials. Experimental results have revealed strong wavelength-dependent photoresponses in all previous reports. This limits the potential application of broadband photosensors. Therefore, finding a wavelength-insensitive photosensor is imperative in this application. Photocurrent measurements were performed in Sb2Te3 flakes at various wavelengths ranging from visible to near IR light. The measured photocurrent change was insensitive to wavelengths from 300 to 1000 nm. The observed wavelength response deviation was lower than that in all previous reports. Our results show that the corresponding energies of these photocurrent peaks are consistent with the energy difference of the density of state peaks between conduction and valence bands. This suggests that the observed photocurrent originates from these band structure peak transitions under light illumination. Contrary to the most common explanation that observed broadband photocurrent carrier is mainly from the surface state in low-dimensional materials, our experimental result suggests that bulk state band structure is the main source of the observed photocurrent and dominates the broadband photocurrent.

All-out band structure and band offset ab initio predictions for AlN/GaN and AlP/GaP interfaces

2013 ◽  
Vol 114 (3) ◽  
pp. 033709 ◽  
Author(s):  
O. P. Silva Filho ◽  
M. Ribeiro ◽  
R. R. Pelá ◽  
L. K. Teles ◽  
L. G. Ferreira ◽  
...  
Keyword(s):  
Band Structure ◽  
Ab Initio ◽  
Band Offset
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