Band Offsets In GaN/AlN and AlN/SiC Heterojunctions

1997 ◽  
Vol 482 ◽  
Author(s):  
Nadia Binggeli ◽  
Philippe Ferrara ◽  
Alfonso Baldereschi
Keyword(s):  
Interface Layer ◽  
Band Alignment ◽  
Band Offset ◽  
Band Offsets ◽  
Conduction Band Offset ◽  
Bulk Strain ◽  
Minor Influence ◽  
Atomic Relaxation ◽  
Interface Orientation ◽  
A Minor

AbstractWe have investigated the structural trends of the band offsets in GaN/AlN and AlN/SiC heterojunctions using the ab initio pseudopotential method. In the zincblende GaN/AlN (100), (110), and (111) heterojunctions, the band offsets are relatively insensitive to interface orientation. Bulk strain effects, however, can modify the offset by as much as 0.4 eV in coherently strained AlN/GaN and GaN/AlN (100) junctions. The band alignment in the heterovalent AlN/SiC (110) and (111) heterojunctions depends on the geometry and stoichiometry of the interface. Valence band offsets as high as 2.5 eV are obtained for neutral AlN/SiC(11) junctions with a mixed Al/Si interface layer and as low as 1.3 eV with a mixed N/C layer. Atomic relaxation plays a major role in determining the offset. The change from zincblende (111) to wurtzite (0001) crystal structure in GaN/AlN and AlN/SiC heterojunctions selectively affects the conduction band offset, and has only a minor influence on the valence discontinuity.

Investigation of GaNAsSb/GaAs and GaInNAsSb/GaNAs/GaAs Band Offsets

2005 ◽  
Vol 864 ◽  
Author(s):  
Homan B. Yuen ◽  
Robert Kudrawiec ◽  
K. Ryczko ◽  
S.R. Bank ◽  
M.A. Wistey ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Plasma Source ◽  
Nitrogen Plasma ◽  
Band Offset ◽  
Dilute Nitride ◽  
Band Offsets ◽  
Conduction Band Offset ◽  
Energy Transitions ◽  
Gaas Structure ◽  
Gaas Laser

AbstractHeterojunction band offsets of GaNAsSb/GaAs, GaInNAsSb/GaAs, and GaInNAsSb/GaNAs/GaAs quantum well (QW) structures were measured by photoreflectance (PR) spectroscopy. These samples were grown by solid-source molecular beam epitaxy using a radio-frequency nitrogen plasma source. PR spectra were collected from the QW structures and the energy transitions were obtained. The experimental data of the QW energy transitions were analyzed by theoretical calculations. Using predetermined values such as QW thickness and composition, unknown factors such as the heterojunction band offsets were able to be determined. For the GaN0.02As0.87Sb0.11/GaAs structure, we found that Qc≈0.5. For Ga0.62In0.38N0.026As0.954Sb0.02/GaAs, we found that Qc≈0.8. This value is similar to the antimony free dilute-nitride material GaInNAs since the small amount of antimony does not affect the band offsets. For the technologically important Ga0.61In0.39N0.023As0.957Sb0.02/GaN0.027As0.973/GaAs laser structure, we found that the GaInNAsSb/GaNAs QW had a conduction band offset of 144 meV and a valence band offset of 127 meV. With a greater understanding of the band structure, more advanced GaInNAsSb laser devices can be obtained.

scholarly journals Interface Structure and Band Alignment of CZTS/CdS Heterojunction: An Experimental and First-Principles DFT Investigation

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4040 ◽  
Author(s):  
Sachin Rondiya ◽  
Yogesh Jadhav ◽  
Mamta Nasane ◽  
Sandesh Jadkar ◽  
Nelson Y. Dzade
Keyword(s):  
Dft Calculations ◽  
First Principles ◽  
Density Functional ◽  
Rf Sputtering ◽  
Band Alignment ◽  
Charge Carriers ◽  
Band Offsets ◽  
Conduction Band Offset ◽  
Cv Measurements ◽  
Czts Thin Films

We report a phase-pure kesterite Cu2ZnSnS4 (CZTS) thin films, synthesized using radio frequency (RF) sputtering followed by low-temperature H2S annealing and confirmed by XRD, Raman spectroscopy and XPS measurements. Subsequently, the band offsets at the interface of the CZTS/CdS heterojunction were systematically investigated by combining experiments and first-principles density functional theory (DFT) calculations, which provide atomic-level insights into the nature of atomic ordering and stability of the CZTS/CdS interface. A staggered type II band alignment between the valence and conduction bands at the CZTS/CdS interface was determined from Cyclic Voltammetry (CV) measurements and the DFT calculations. The conduction and valence band offsets were estimated at 0.10 and 1.21 eV, respectively, from CV measurements and 0.28 and 1.15 from DFT prediction. Based on the small conduction band offset and the predicted higher positions of the VBmax and CBmin for CZTS than CdS, it is suggested photogenerated charge carriers will be efficient separated across the interface, where electrons will flow from CZTS to the CdS and and vice versa for photo-generated valence holes. Our results help to explain the separation of photo-excited charge carriers across the CZTS/CdS interface and it should open new avenues for developing more efficient CZTS-based solar cells.

Impact of Interface Defect Passivation on Conduction Band Offset at SiO2/4H-SiC Interface

2012 ◽  
Vol 717-720 ◽  
pp. 721-724 ◽  
Author(s):  
Takuji Hosoi ◽  
Takashi Kirino ◽  
Atthawut Chanthaphan ◽  
Yusuke Uenishi ◽  
Daisuke Ikeguchi ◽  
...  
Keyword(s):  
Conduction Band ◽  
Photoelectron Spectroscopy ◽  
Hydrogen Gas ◽  
Band Alignment ◽  
Band Offset ◽  
Partial Recovery ◽  
Conduction Band Offset ◽  
Interface Defect ◽  
Defect Passivation ◽  
Thermally Grown

The change in energy band alignment of thermally grown SiO2/4H-SiC(0001) structures due to an interface defect passivation treatment was investigated by means of synchrotron radiation photoelectron spectroscopy (SR-PES) and electrical characterization. Although both negative fixed charge and interface state density in SiO2/SiC structures were effectively reduced by high-temparature hydrogen gas annealing (FGA), the conduction band offset (ΔEc) at the SiO2/SiC interface was found to be decreased by about 0.1 eV after FGA. In addition, a subsequent vacuum annealing to induce hydrogen desorption from the interface resulted in not only a slight degradation in interface property but also a partial recovery of ΔEc value. These results indicate that the hydrogen passivation of negatively charged defects near the thermally grown SiO2/SiC interface causes the reduction in conduction band offset. Therefore, the tradeoff between interface quality and conduction band offset for thermally grown SiO2/SiC MOS structure needs to be considered for developing SiC MOS devices.

Band alignment at amorphous/crystalline silicon hetero-interfaces

2011 ◽  
Vol 1321 ◽  
Author(s):  
L. Korte ◽  
T. F. Schulze ◽  
C. Leendertz ◽  
M. Schmidt ◽  
B. Rech
Keyword(s):  
Photoelectron Spectroscopy ◽  
Experimental Error ◽  
Crystalline Silicon ◽  
Band Alignment ◽  
Low Energy ◽  
Surface Photovoltage ◽  
Band Offset ◽  
Conduction Band Offset ◽  
Silicon Heterojunctions ◽  
Deposition Conditions

ABSTRACTWe present an investigation of the band offsets in amorphous/crystalline silicon heterojunctions (a-Si:H/c-Si) using low energy photoelectron spectroscopy, ellipsometry and surface photovoltage data. For a variation of deposition conditions that lead to changes in hydrogen content and the thereby the a-Si:H band gap by ∼180 meV, we find that mainly the conduction band offset ΔEV varies, while ΔEC stays constant within experimental error. This result can be understood in the framework of charge neutrality (CNL) band lineup theory.

Electronic Properties of GaN (0001) – Dielectric Interfaces

2004 ◽  
Vol 14 (01) ◽  
pp. 107-125 ◽  
Author(s):  
T. E. Cook ◽  
C. C. Fulton ◽  
W. J. Mecouch ◽  
R. F. Davis ◽  
G. Lucovsky ◽  
...  
Keyword(s):  
Electron Affinity ◽  
Photoelectron Spectroscopy ◽  
Band Alignment ◽  
Band Offset ◽  
Energy Bands ◽  
Interface Dipole ◽  
Conduction Band Offset ◽  
Dielectric Interfaces ◽  
P Type ◽  
Interface Type

The characteristics of clean n- and p-type GaN (0001) surfaces and the interface between this surface and SiO 2, Si 3 N 4, and HfO 2 have been investigated. Layers of SiO 2, Si3 N 4, or HfO 2 were carefully deposited to limit the reaction between the film and clean GaN surfaces. After stepwise deposition, the electronic states were measured with x-ray photoelectron spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS). A valence band offset (VBO) of 2.0±0.2 eV with a conduction band offset (CBO) of 3.6±0.2 eV was determined for the GaN / SiO 2 interface. The large band offsets suggest SiO 2 is an excellent candidate for passivation of GaN . For the GaN / Si 3 N 4, interface, type II band alignment was observed with a VBO of -0.5±0.2 eV and a CBO of 2.4±0.2 eV . While Si3 N 4 should passivate n-type GaN surfaces, it may not be appropriate for p-type GaN surfaces. A VBO of 0.3±0.2 eV with a CBO of 2.1±0.2 eV was determined for the annealed GaN / HfO 2 interface. An instability was observed in the HfO 2 film, with energy bands shifting ~0.4 eV during a 650°C densification anneal. The electron affinity measurements via UPS were 3.0, 1.1, 1.8, and 2.9±0.1 eV for GaN , SiO 2, Si 3 N 4, and HfO 2 surfaces, respectively. The deduced band alignments were compared to the predictions of the electron affinity model and deviations were attributed to a change of the interface dipole. Interface dipoles contributed 1.6, 1.1 and 2.0±0.2 eV to the band alignment of the GaN / SiO 2, GaN / Si 3 N 4, and GaN / HfO 2 interfaces, respectively. It was noted that the existence of Ga-O bonding at the heterojunction could significantly affect the interface dipole, and consequently the band alignment in relation to the GaN .

Energy Band Offsets at a Ga2O3(Gd2O3)-GaAs Interface

1999 ◽  
Vol 573 ◽  
Author(s):  
T. S. Lay ◽  
M. Hong ◽  
J. Kwo ◽  
J. P. Mannaerts ◽  
W. H. Hung ◽  
...  
Keyword(s):  
Energy Band ◽  
Oxide Semiconductor ◽  
Band Offset ◽  
Spectroscopy Analysis ◽  
Valence Band Offset ◽  
Electron Effective Mass ◽  
Band Offsets ◽  
Conduction Band Offset ◽  
Current Voltage ◽  
Current Voltage Characteristics

ABSTRACTWe report the energy band offsets at a Ga2O3(Gd2O3)-GaAs interface. The valence-band offset (ΔEv) is ∼ 2.6 eV, measured by soft x-ray photoemission spectroscopy. Analysis of the current-voltage characteristics of a Pt-Ga2O3(Gd2O3)-GaAs MOS (metal-oxide-semiconductor) structure, which are dominated by Fowler-Nordheim tunneling, reveals a conduction-band offset (ΔEC) ∼ 1.4 eV at the Ga2O3(Gd2O3)-GaAs interface and an electron effective mass (m*) ∼ 0.29 me of the Ga2O3(Gd2O3) film.

Band Alignment of CdS/Cu2ZnSnSe4 Heterointerface and Solar Cell Performances

MRS Advances ◽  
2017 ◽  
Vol 2 (53) ◽  
pp. 3157-3162 ◽  
Author(s):  
Takehiko Nagai ◽  
Shinho Kim ◽  
Hitoshi Tampo ◽  
Kang Min Kim ◽  
Hajime Shibata ◽  
...  
Keyword(s):  
Conduction Band ◽  
Band Alignment ◽  
Photoemission Spectroscopy ◽  
Band Offset ◽  
Valence Band Offset ◽  
X Ray ◽  
Heterojunction Solar Cells ◽  
Conduction Band Offset ◽  
Ultraviolet Photoemission Spectroscopy ◽  
Large Spike

ABSTRACTWe determined that the conduction band offset (CBO) and the valence band offset (VBO) at the CdS/ Cu2ZnSnSe4 (CZTSe) heterointerface are +0.56 and +0.89eV, respectively, by using X-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS) and inversed photoemission spectroscopy (IPES). A positive CBO value, so-called “spike” structure, means that the position of conduction band becomes higher than that of absorber layer. The evaluated CBO of +0.56 eV suggests that the conduction band alignment at CdS/CZTSe interface is enough to become an electron barrier. Despite such a large spike structure in the conduction band at the interface, a conversion efficiency of 8.7 % could be obtained for the CdS/CZTSe heterojunction solar cells.

scholarly journals Analytical study of effect of energy band parameters and lattice temperature on conduction band offset in AlN/Ga2O3 HEMT

2021 ◽  
Vol 34 (3) ◽  
pp. 323-332
Author(s):  
Rajan Singh ◽  
Trupti Lenka ◽  
Hieu Nguyen
Keyword(s):  
Schottky Barrier ◽  
Conduction Band ◽  
Energy Band ◽  
Analytical Study ◽  
Band Alignment ◽  
Lattice Temperature ◽  
Band Offset ◽  
Conduction Band Offset ◽  
Energy Bandgap ◽  
2Deg Density

Apart from other factors, band alignment led conduction band offset (CBO) largely affects the two dimensional electron gas (2DEG) density ns in wide bandgap semiconductor based high electron mobility transistors (HEMTs). In the context of assessing various performance metrics of HEMTs, rational estimation of CBO and maximum achievable 2DEG density is critical. Here, we present an analytical study on the effect of different energy band parameters-energy bandgap and electron affinity of heterostructure constituents, and lattice temperature on CBO and estimated 2DEG density in quantum triangular-well. It is found that at thermal equilibrium, ns increases linearly with ?EC at a fixed Schottky barrier potential, but decreases linearly with increasing gate-metal work function even at fixed ?EC, due to increased Schottky barrier heights. Furthermore, it is also observed that poor thermal conductivity led to higher lattice temperature which results in lower energy bandgap, and hence affects ?EC and ns at higher output currents.

Measurements of the Band Offset of SiO2 on Clean GaN

2001 ◽  
Vol 693 ◽  
Author(s):  
E.H. Hurt ◽  
Ted E. Cook ◽  
K.M. Tracy ◽  
R.F. Davis ◽  
G. Lucovsky ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Electronic States ◽  
Band Alignment ◽  
Gate Insulator ◽  
Band Offset ◽  
Valence Band Offset ◽  
Band Bending ◽  
Analysis Techniques ◽  
Conduction Band Offset ◽  
Surface Analysis Techniques

AbstractThe band alignment of SiO2 and GaN is important for passivation of high voltage devices and for gate insulator applications. In this study XPS and UPS techniques are employed to determine the electronic states as SiO2 is deposited onto a clean GaN surface. The substrate was epitaxially grown n-type GaN on 6H-SiC (0001) substrates with an AlN (0001) buffer layer. The GaN surface was atomically cleaned via a 860°C anneal in an NH3 atmosphere. For the clean GaN surface, upward band bending of ~0.3 ±0.1 eV was measured, and the electron affinity was measured to be ~2.9 eV. Layers of Si were deposited on the GaN surface via Molecular Beam Epitaxy (MBE), and the Si was oxidized by a remote O2 plasma. The oxidation of the Si occurred without oxidizing the GaN. Densification of the created SiO2 film was achieved by annealing the substrate at 650°C. Surface analysis techniques were performed after each process, and yielded a valence band offset of ~2.0 eV, and a conduction band offset of ~3.6 eV for the GaN-SiO2 interface.

scholarly journals Terahertz Pulse Emission from Semiconductor Heterostructures Caused by Ballistic Photocurrents

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4067
Author(s):  
Vitaly Leonidovich Malevich ◽  
Pavel Aliaksandravich Ziaziulia ◽  
Ričardas Norkus ◽  
Vaidas Pačebutas ◽  
Ignas Nevinskas ◽  
...  
Keyword(s):  
Energy Band ◽  
Wide Bandgap ◽  
Semiconductor Heterostructures ◽  
Band Offset ◽  
Terahertz Pulse ◽  
Pulse Emission ◽  
Polarity Inversion ◽  
Band Offsets ◽  
Conduction Band Offset ◽  
Narrow Bandgap

Terahertz radiation pulses emitted after exciting semiconductor heterostructures by femtosecond optical pulses were used to determine the electron energy band offsets between different constituent materials. It has been shown that when the photon energy is sufficient enough to excite electrons in the narrower bandgap layer with an energy greater than the conduction band offset, the terahertz pulse changes its polarity. Theoretical analysis performed both analytically and by numerical Monte Carlo simulation has shown that the polarity inversion is caused by the electrons that are excited in the narrow bandgap layer with energies sufficient to surmount the band offset with the wide bandgap substrate. This effect is used to evaluate the energy band offsets in GaInAs/InP and GaInAsBi/InP heterostructures.

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