scholarly journals Built-in electric fields and valence band offsets in InN/GaN(0001) superlattices: First-principles investigations

2011 ◽  
Vol 109 (8) ◽  
pp. 083721 ◽  
Author(s):  
C. C. Shieh ◽  
X. Y. Cui ◽  
B. Delley ◽  
C. Stampfl
Keyword(s):  
Valence Band ◽  
Electric Fields ◽  
First Principles ◽  
Band Offsets

Absorption and optical conduction in InSe/ZnSe/InSe thin film transistors

2016 ◽  
Vol 09 (02) ◽  
pp. 1650019 ◽  
Author(s):  
S. E. Al Garni ◽  
A. F. Qasrawi
Keyword(s):  
Thin Film ◽  
Valence Band ◽  
Electric Fields ◽  
Optical Conductivity ◽  
Thin Film Transistor ◽  
Free Carrier Absorption ◽  
Band Offsets ◽  
Dielectric Spectra ◽  
X Ray ◽  
Alternating Electric Fields

In this work, (n)InSe/(p)ZnSe and (n)InSe/(p)ZnSe/(n)InSe heterojunction thin film transistor (TFT) devices are produced by the thermal evaporation technique. They are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion X-ray spectroscopy and optical spectroscopy techniques. While the InSe films are found to be amorphous, the ZnSe and InSe/ZnSe films exhibited polycrystalline nature of crystallization. The optical analysis has shown that these devices exhibit a conduction band offsets of 0.47 and valence band offsets of 0.67 and 0.74[Formula: see text]eV, respectively. In addition, while the dielectric spectra of the InSe and ZnSe displayed resonance peaks at 416 and 528[Formula: see text]THz, the dielectric spectra of InSe/ZnSe and InSe/ZnSe/InSe layers indicated two additional peaks at 305 and 350[Formula: see text]THz, respectively. On the other hand, the optical conductivity analysis and modeling in the light of free carrier absorption theory reflected low values of drift mobilities associated with incident alternating electric fields at terahertz frequencies. The drift mobility of the charge carrier particles at femtoseconds scattering times increased as a result of the ZnSe sandwiching between two InSe layers. The valence band offsets, the dielectric resonance at 305 and 350[Formula: see text]THz and the optical conductivity values nominate TFT devices for use in optoelectronics.

Effects of Substrate Orientation on the Valence Band Splittings and Valence Band Offsets in GaN and AlN Films

1997 ◽  
Vol 482 ◽  
Author(s):  
J. A. Majewski ◽  
M. Städele
Keyword(s):  
Valence Band ◽  
Conduction Band ◽  
First Principles ◽  
Stacking Fault ◽  
Type I ◽  
Band Offsets ◽  
Substrate Orientation ◽  
First Principles Study

AbstractWe present a first-principles study of heteroepitaxial interfaces between GaN and both cubic as well as wurtzite AlN substrates oriented along main cubic or hexagonal directions and of stacking fault interfaces between cubic and wurtzite GaN. Our calculations show that all studied heterostructures are of type I. Valence band offsets for GaN/AlN are nearly independent of the substrate orientation and of the order of 0.8 eV. The valence and conduction band offsets for a stacking fault interface are predicted to be 40 meV and 175 meV, respectively.

Electric fields at the SiC/AlN and SiC/GaN polar interfaces

2000 ◽  
Vol 639 ◽  
Author(s):  
Morad Rouhani Laridjani ◽  
Pierre Masri ◽  
Jacek A. Majewski
Keyword(s):  
Electronic Properties ◽  
Valence Band ◽  
Electric Fields ◽  
Mixed Layer ◽  
First Principles ◽  
Type I ◽  
First Principles Calculations ◽  
Interface Charges ◽  
Structural And Electronic Properties

ABSTRACTWe present first-principles calculations of structural and electronic properties of heterovalent SiC/AlN and SiC/GaN heterostructures with wurtzite AlN and GaN films pseudomorphically grown on the 6H-SiC and 3C-SiC substrates along the c-axis. We have investigated reconstructed stoichiometric interfaces consisting of one mixed layer with various lateral arrangements. The preferred bonding configurations of the reconstructed interfaces are found to be Si-N and Ga-C. The calculated valence band discontinuities for SiC/AlN and SiC/GaN heterostructures lie in the range of 1.5 - 2.3 eV and 0.4 - 1.4 eV, respectively. The SiC/AlN heterostructures are predicted to be of type I, whereas SiC/GaN heterostructures can be of type I or II. The polarization induced interface charges are of the order of 4.8 × 1012cm−2 and 0.7 × 1012 cm−2 in SiC/AlN and SiC/GaN junctions, respectively.

scholarly journals Electric fields and valence-band offsets at strained [111] heterojunctions

1997 ◽  
Vol 55 (19) ◽  
pp. 13080-13087 ◽  
Author(s):  
S. Picozzi ◽  
A. Continenza ◽  
A. J. Freeman
Keyword(s):  
Valence Band ◽  
Electric Fields ◽  
Band Offsets

scholarly journals Offsets and Polarization at Strained AlN/GaN Polar Interfaces

1996 ◽  
Vol 449 ◽  
Author(s):  
Fabio Bernardini ◽  
Vincenzo Fiorentini ◽  
David Vanderbilt
Keyword(s):  
Valence Band ◽  
Geometric Structure ◽  
First Principles ◽  
Lattice Mismatch ◽  
First Principles Calculation ◽  
Band Offsets ◽  
Piezoelectric Fields ◽  
Formation Energies

ABSTRACTThe strain induced by lattice mismatch at the interface is responsible for the different value of the band discontinuities observed recently for the AlN/GaN (AlN on GaN) and the GaN/AlN (GaN on AlN) polar (0001) interface. We present a first-principles calculation of valence band offsets, interface dipoles, strain-induced piezoelectric fields, relaxed geometric structure, and formation energies. Our results confirm the existence of a large forward-backward asymmetry for this interface.

Stability and Band Offsets of SiC/GaN, SiC/AlN, and AlN/GaN Heterostructures

1996 ◽  
Vol 449 ◽  
Author(s):  
J. A. Majewski ◽  
M. Städele ◽  
P. Vogl
Keyword(s):  
Valence Band ◽  
First Principles ◽  
Valence Band Maximum ◽  
Type I ◽  
First Principles Calculations ◽  
Band Offsets ◽  
Structural And Electronic Properties ◽  
Transitivity Rule ◽  
Gan Heterostructure ◽  
Mixed Layers

ABSTRACTWe present first-principles calculations of structural and electronic properties of heterova-lent SiC/GaN, SiC/AIN, and isovalent AIN/GaN heterostructures that are grown pseudo-morphically on (001) or (110) SiC substrates. For the polar interfaces, we have investigated reconstructed stoichiometric interfaces consisting of one and two mixed layers with lateral c(2 × 2), 2 × 1, 1 × 2, and 2 × 2 arrangements. The preferred bonding configurations of the reconstructed interfaces are found to be Si-N and Ga-C. With respect to vacuum, the valence band maximum is found to be highest in SiC and lowest in A1N. In these systems, the valence band offsets deviate substantially from the transitivity rule and depend sensitively on the microscopic details of the interface geometry. The SiC/AIN and AIN/GaN heterostructures are predicted to be of type I, whereas SiC/GaN heterostructure can be of type I or II.

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