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.

Free excitons in strained MOCVD-grown GaN layers

2003 ◽  
Vol 8 ◽  
Author(s):  
N.N. Syrbu ◽  
I.M. Tiginyanu ◽  
V.V. Ursaki ◽  
V.V. Zalamai ◽  
Veaceslav Popa ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
High Resolution ◽  
Absorption Spectra ◽  
Conduction Band ◽  
Thin Layers ◽  
Effective Masses ◽  
Sapphire Substrates ◽  
Electron Transitions ◽  
Valence Bands ◽  
S States

GaN layers grown on sapphire substrates were characterized using high resolution optical reflectivity and absorption spectroscopy in the region of ground and excited exciton states. The main exciton parameters are deduced from calculations of reflectivity contours for A and B exciton S-states. The parameters of the Γ5 state of the A-exciton as well as those of the Γ5 and Γ1 states of the B-exciton are determined from a comparative analysis of reflectivity and absorption spectra in thin layers. The influence of strains inherent to MOCVD-grown GaN layers on the exciton parameters including effective masses and longitudinal-transverse splitting is discussed. Electron transitions from the three (Γ9, Γ7, Γ7) upper valence bands to the second Ec2 conduction band of Γ3 symmetry were evidenced.

Valence electron energy loss spectroscopy in reflection geometry

1989 ◽  
Vol 47 ◽  
pp. 378-379
Author(s):  
J. Liu ◽  
J. M. Cowley
Keyword(s):  
Energy Loss ◽  
Valence Electron ◽  
Interband Transition ◽  
Specular Reflection ◽  
Three Dimensional ◽  
Electron Excitation ◽  
Transmission Electron ◽  
Yield Information ◽  
Valence Bands ◽  
Excitation Processes

The low energy loss region of a EELS spectrum carries information about the valence electron excitation processes (e.g., collective excitations for free electron like materials and interband transitions for insulators). The relative intensities and the positions of the interband transition energy loss peaks observed in EELS spectra are determined by the joint density of states (DOS) of the initial and final states of the excitation processes. Thus it is expected that EELS in reflection mode could yield information about the perturbation of the DOS of the conduction and valence bands of the bulk crystals caused by the termination of the three dimensional periodicity at the crystal surfaces. The experiments were performed in a Philipps 400T transmission electron microscope operated at 120 kV. The reflection EELS spectra were obtained by a Gatan 607 EELS spectrometer together with a Tracor data acquisition system and the resolution of the spectrometer was about 0.8 eV. All the reflection spectra are obtained from the specular reflection spots satisfying surface resonance conditions.

Photoemission study on the valence bands of DMe-DCNQI derived charge-transfer salts

1991 ◽  
Vol 1 (9) ◽  
pp. 1347-1354 ◽  
Author(s):  
D. Schmeißer ◽  
A. Gonzales ◽  
J. U. von Schütz ◽  
H. Wachtel ◽  
H. C. Wolf
Keyword(s):  
Charge Transfer ◽  
Charge Transfer Salts ◽  
Valence Bands ◽  
Photoemission Study

Hybrid Valence Bands in Strained-Layer Heterostructures grown on Relaxed SiGe Virtual Substrates

2003 ◽  
Vol 765 ◽  
Author(s):  
Minjoo L. Lee ◽  
Eugene A. Fitzgerald
Keyword(s):  
Strained Silicon ◽  
Strained Layer ◽  
Dual Channel ◽  
Enhanced Mobility ◽  
Valence Bands ◽  
Almost All

AbstractThe use of alternative channel materials such as germanium [1,2] and strained silicon (ε-Si) [3-5] is increasingly being considered as a method for improving the performance of MOSFETs. While ε-Si grown on relaxed Si1-x Gex is drawing closer to widespread commercialization, it is currently believed that almost all of the performance benefit in CMOS implementations will derive from the enhanced mobility of the n -MOSFET [5]. In this paper, we demonstrate that ε-Si p -MOSFETs can be engineered to exhibit mobility enhancements that increase or remain constant as a function of inversion density. We have also designed and fabricated ε-Si / ε-Ge dual-channel p -MOSFETs exhibiting mobility enhancements of 10 times. These p -MOSFETs can be integrated on the same wafers as ε-Si n -MOSFETs, making symmetric-mobility CMOS possible.

EXPERIMENTAL VERIFICATION OF DLTS MODELS

2019 ◽  
Author(s):  
Nataliya Mitina ◽  
Vladimir Krylov
Keyword(s):  
Activation Energy ◽  
Gallium Arsenide ◽  
Data Processing ◽  
Experimental Verification ◽  
Deep Level ◽  
Deep Levels ◽  
Transient Spectroscopy

The results of an experiment to determine the activation energy of a deep level in a gallium arsenide mesastructure, obtained by the method of capacitive deep levels transient spectroscopy with data processing according to the Oreshkin model and Lang model, are considered.

DEEP LEVELS' ACTIVATION ENERGY DEPENDENCE ON MEASUREMENT MODES

2019 ◽  
Author(s):  
Aleksey Bogachev ◽  
Vladimir Krylov
Keyword(s):  
Activation Energy ◽  
Gallium Arsenide ◽  
Energy Dependence ◽  
Deep Level ◽  
Deep Levels ◽  
Blocking Voltage

The results of an experiment to determine the activation energy of a deep level in a gallium arsenide mesastructure by capacitive relaxation spectroscopy of deep levels at various values of the blocking voltage are considered.

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