Terahertz Pulse Emission from Semiconductor Heterostructures Caused by Ballistic Photocurrents

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

MRS Proceedings ◽

10.1557/proc-573-131 ◽

1999 ◽

Vol 573 ◽

Cited By ~ 5

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.

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

MRS Proceedings ◽

10.1557/proc-864-e3.3 ◽

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.

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Conduction band offset engineering in wide-bandgap Ag(In,Ga)Se2solar cells by hybrid buffer layer

Japanese Journal of Applied Physics ◽

10.7567/jjap.56.08mc09 ◽

2017 ◽

Vol 56 (8S2) ◽

pp. 08MC09 ◽

Cited By ~ 5

Author(s):

Takeshi Umehara ◽

Faris Akira Bin Mohd Zulkifly ◽

Kazuyoshi Nakada ◽

Akira Yamada

Keyword(s):

Buffer Layer ◽

Conduction Band ◽

Wide Bandgap ◽

Band Offset ◽

Conduction Band Offset

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

Facta universitatis - series Electronics and Energetics ◽

10.2298/fuee2103323s ◽

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.

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Chemical Composition and Electronic Properties of CuInS2/Zn(S,O) Interfaces

MRS Proceedings ◽

10.1557/proc-1165-m03-07 ◽

2009 ◽

Vol 1165 ◽

Cited By ~ 2

Author(s):

Rodrigo Sáez-Araoz ◽

Iver Lauermann ◽

Axel Neisser ◽

Martha Ch Lux-Steiner ◽

Ahmed Ennaoui

Keyword(s):

Chemical Composition ◽

Band Gap ◽

Conduction Band ◽

Photoelectron Spectroscopy ◽

Energy Band ◽

Band Offset ◽

Energy Band Gap ◽

Valence Band Offset ◽

X Ray ◽

Conduction Band Offset

AbstractWe report on the chemical deposition and electronic properties of CuInS2/Zn(S,O) interfaces. The Zn(S,O) buffer was grown by a new chemical bath deposition (CBD) process that allows the tailoring of the S/O ratio in the films. Resulting Zn(S,O) films exhibit transparencies above 80% (for λ>390 nm) and an optical energy band gap of 3.9 eV which decreases to 3.6 eV after annealing in air at 200°C. Production line CuInS2 (CIS) absorbers provided by Sulfurcell Solartechnik GmbH are used as substrates for the investigation of the CIS/Zn(S,O) interface and the chemical composition of Zn(S,O). A ZnS/(ZnS+ZnO) ratio of 0.5 is found by X-ray photoelectron spectroscopy and X-ray excited Auger electron spectroscopy (XPS and XAES). The valence band offset between the heterojunction partners (ΔEV = 1.8 ± 0.2 eV) has been determined by means of XPS and ultraviolet photoelectron spectroscopy (UPS). Considering the energy band gap of the CIS absorber and the measured band gap of Zn(S,O), the conduction band offset (ΔEC) is calculated as: resulting in a spike of 0.5±0.3 eV in the conduction band at the heterojunction before annealing. After the heat treatment, the valence band offset is reduced to 1.5±0.2 eV and the calculated conduction band offset remains at 0.5±0.3 eV.

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Band Offsets In GaN/AlN and AlN/SiC Heterojunctions

MRS Proceedings ◽

10.1557/proc-482-911 ◽

1997 ◽

Vol 482 ◽

Cited By ~ 4

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.

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Conduction band offset-dependent induced threshold voltage shifts in a-InGaZnO TFTs under positive bias illumination stress

AIP Advances ◽

10.1063/5.0035379 ◽

2021 ◽

Vol 11 (3) ◽

pp. 035312

Author(s):

Hyojung Kim ◽

Soonkon Kim ◽

Jongmin Yoo ◽

Changyong Oh ◽

Bosung Kim ◽

...

Keyword(s):

Conduction Band ◽

Threshold Voltage ◽

Band Offset ◽

Positive Bias ◽

Conduction Band Offset

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Calculated effect of conduction-band offset on CuInSe2 solar-cell performance

10.1063/1.49373 ◽

1996 ◽

Cited By ~ 20

Author(s):

Xiaoxiang Liu ◽

James R. Sites

Keyword(s):

Solar Cell ◽

Conduction Band ◽

Cell Performance ◽

Band Offset ◽

Solar Cell Performance ◽

Conduction Band Offset ◽

Calculated Effect

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Effect of Interface States on the Open-Circuit Volatage in a-Si:H/c-Si Heterojunction Solar Cells

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.485.454 ◽

2012 ◽

Vol 485 ◽

pp. 454-456

Author(s):

Lan E Luo ◽

Chun Liang Zhong

Keyword(s):

Open Circuit Voltage ◽

Minority Carrier ◽

Interface States ◽

Open Circuit ◽

Band Offset ◽

Heterojunction Solar Cells ◽

Conduction Band Offset ◽

Photovoltaic Application ◽

Critical Issues ◽

Recombination Centers

The properties of the a-Si:H/c-Si interface are one of the critical issues for the photovoltaic application. The effects of the interface states on the open-circuit voltage VOC were performed by a set of simulations. VOC decreases with Dit increasing, especially at high values of Dit, since the interface states act as recombination centers to decrease the excess minority carrier density in c-Si. Since the conduction band offset ∆EC can saturate part of interface states, VOC increasing with ∆EC increasing.

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