NOVEL MEASUREMENT OF THE BAND DISCONTINUITIES IN (Al,Ga)As HETEROJUNCTIONS

1985 ◽  
Vol 56 ◽  
Author(s):  
B. A. WILSON ◽  
P. DAWSON ◽  
C. W. TU ◽  
R. C. MILLER
Keyword(s):  
Valence Band ◽  
Binding Energies ◽  
Band Alignment ◽  
Material System ◽  
Valence Band Offset ◽  
Quantum Well Structures ◽  
Accurate Knowledge ◽  
Novel Method ◽  
Band Alignments ◽  
Valence Band Discontinuity

AbstractA novel method has been used to obtain a direct and accurate measure of the valence-band discontinuity AlyGa1−yAs/AlAs heterojunctions in quantum-well structures. The technique takes advantage of the crossover occurring at a critical Al concentration above which the indirect X minimum in the AlAs becomes the lowest-energy conduction band in the system. Within these “staggered” band alignment structures, photoexcited electrons and holes are spatially separated, and recombination occurs across the interface. The resulting emission fixes the valence-band offset to within 1% without accurate knowledge of other system parameters, such as effective masses and exciton or dopant binding energies. These measurements represent the first direct optical confirmation of staggered band alignments in this technologically important material system.

scholarly journals Investigation of Band Alignment for Hybrid 2D-MoS2/3D-β-Ga2O3 Heterojunctions with Nitridation

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Ya-Wei Huan ◽  
Ke Xu ◽  
Wen-Jun Liu ◽  
Hao Zhang ◽  
Dmitriy Anatolyevich Golosov ◽  
...  
Keyword(s):  
Valence Band ◽  
Transition Metal Dichalcogenides ◽  
Three Dimensional ◽  
Optoelectronic Devices ◽  
Band Alignment ◽  
Band Offsets ◽  
Group Iii ◽  
Nanoelectronic Devices ◽  
Metal Dichalcogenides ◽  
Band Alignments

AbstractHybrid heterojunctions based on two-dimensional (2D) and conventional three-dimensional (3D) materials provide a promising way toward nanoelectronic devices with engineered features. In this work, we investigated the band alignment of a mixed-dimensional heterojunction composed of transferred MoS2 on β-Ga2O3($$ 2- $$2-01) with and without nitridation. The conduction and valence band offsets for unnitrided 2D-MoS2/3D-β-Ga2O3 heterojunction were determined to be respectively 0.43 ± 0.1 and 2.87 ± 0.1 eV. For the nitrided heterojunction, the conduction and valence band offsets were deduced to 0.68 ± 0.1 and 2.62 ± 0.1 eV, respectively. The modified band alignment could result from the dipole formed by charge transfer across the heterojunction interface. The effect of nitridation on the band alignments between group III oxides and transition metal dichalcogenides will supply feasible technical routes for designing their heterojunction-based electronic and optoelectronic devices.

Growth and Characterization of the Binary Defect Alloy Cu2-xSe and the Relation to II–VI/I–III–VI Heterojunction Formation

1995 ◽  
Vol 378 ◽  
Author(s):  
Art J. Nelson ◽  
K. Sinha ◽  
John Moreland
Keyword(s):  
Electronic Structure ◽  
Valence Band ◽  
Photoemission Spectroscopy ◽  
Interfacial Chemistry ◽  
Valence Band Offset ◽  
Force Microscopy ◽  
Atomic Force ◽  
Valence Band Discontinuity

AbstractSynchrotron radiation soft x-ray photoemission spectroscopy was used to investigate the development of the electronic structure at the CdS/Cu2Se heterojunction interface. Cu2−xSe layers were deposited on GaAs (100) by molecular beam epitaxy from Cu2Se sources. Raman spectra reveal a strong peak at 270 cm−1, indicative of the Cu2−xSe phase. Atomic force microscopy reveals uniaxial growth in a preferred (100) orientation. CdS overlayers were then deposited in-situ, at room temperature, in steps on these epilayers. Photoemission measurements were acquired after each growth in order to observe changes in the valence band electronic structure as well as changes in the Se3d and Cd4d core lines. The results were used to correlate the interfacial chemistry with the electronic structure and to directly determine the CdS/Cu2−xSe and heterojunction valence band discontinuity and the consequent heterojunction band diagram. These results are compared to the valence band offset (ΔEv) for the CdS/CuInSe2 heterojunction interface.

Low-power tunnel field effect transistors using mixed As and Sb based heterostructures

2013 ◽  
Vol 2 (6) ◽  
pp. 637-678 ◽  
Author(s):  
Yan Zhu ◽  
Mantu K. Hudait
Keyword(s):  
Low Power ◽  
Band Gap ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Band Alignment ◽  
Oxide Semiconductor ◽  
Device Performance ◽  
Material System ◽  
Wide Range ◽  
Band Alignments

AbstractReducing supply voltage is a promising way to address the power dissipation in nano-electronic circuits. However, the fundamental lower limit of subthreshold slope (SS) within metal oxide semiconductor field effect transistors (MOSFETs) is a major obstacle to further scaling the operation voltage without degrading ON/OFF ratio in current integrated circuits. Tunnel field-effect transistors (TFETs) benefit from steep switching characteristics due to the quantum-mechanical tunneling injection of carriers from source to channel, rather than by conventional thermionic emission in MOSFETs. TFETs based on group III-V compound semiconductor materials further improve the ON-state current and reduce SS due to the low band gap energies and smaller carrier tunneling mass. The mixed arsenide/antimonide (As/Sb) InxGa1-xAs/GaAsySb1-y heterostructures allow a wide range of band gap energies and various staggered band alignments depending on the alloy compositions in the source and channel materials. Band alignments at source/channel heterointerface can be well modulated by carefully controlling the compositions of the mixed As/Sb material system. In particular, this review introduces and summarizes the progress in the development and optimization of low-power TFETs using mixed As/Sb based heterostructures including basic working principles, design considerations, material growth, interface engineering, material characterization, device fabrication, device performance investigation, band alignment determination, and high temperature reliability. A review of TFETs using mixed As/Sb based heterostructures shows superior structural properties and distinguished device performance, both of which indicate the mixed As/Sb staggered gap TFET as a promising option for high-performance, low-standby power, and energy-efficient logic circuit application.

Exciton binding energies and the valence-band offset in mixed type-I–type-II strained-layer superlattices

1992 ◽  
Vol 46 (3) ◽  
pp. 1557-1563 ◽  
Author(s):  
P. Peyla ◽  
Y. Merle d’Aubigné ◽  
A. Wasiela ◽  
R. Romestain ◽  
H. Mariette ◽  
...  
Keyword(s):  
Valence Band ◽  
Mixed Type ◽  
Binding Energies ◽  
Band Offset ◽  
Type I ◽  
Type Ii ◽  
Valence Band Offset ◽  
Strained Layer ◽  
Strained Layer Superlattices

Optical Investigation of the Band Offset of CdxZn1−xTe /ZnTe and ZnSexTe1−x/ZnTe Superlattices

1990 ◽  
Vol 198 ◽  
Author(s):  
Y. Rajakarunanayake ◽  
M. C. Phillips ◽  
J. O. Mccaldin ◽  
D. H. Chow ◽  
D. A. Collins ◽  
...  
Keyword(s):  
Valence Band ◽  
Band Alignment ◽  
Band Offset ◽  
Type I ◽  
Optical Investigation ◽  
Type Ii ◽  
Carrier Injection ◽  
Valence Band Offset ◽  
Small Component ◽  
Strained Layer Superlattices

ABSTRACTWe have analyzed photoluminescence spectra from CdxZnl−xTe /ZnTe and ZnSexTel−x/ZnTe strained layer superlattices grown by MBE, and obtained the band offsets by fitting to theory. We find that the valence band offset of the CdTe/ZnTe system is quite small (-50± 160 meV). In CdxZnl−xTe /ZnTe superlattices, the electrons and heavy holes are confined in the CdxZn1−xTe layers (type I), while the light holes are confined in the ZnTe layers (type II). On the other hand, the photoluminescence data from the ZnSexTe1−x /ZnTe superlattices suggest that the band alignment is type II, with a large valence band offset (−907 ± 120 meV). We also investigated the band bowing in the ZnSexTel−x alloys by optical spectroscopy, and found that there is only a small component of bowing in the valence band, while most of the bowing occurs in the conduction band. Based on our results for band alignments, we evaluate the prospects for minority carrier injection in wide bandgap heterostructures based on ZnSe, ZnTe, and CdTe.

Pressure dependence of the valence-band discontinuity in GaAs/AlAs and GaAs/AlxGa1−xAs quantum-well structures

1989 ◽  
Vol 39 (8) ◽  
pp. 5546-5549 ◽  
Author(s):  
J. D. Lambkin ◽  
A. R. Adams ◽  
D. J. Dunstan ◽  
P. Dawson ◽  
C. T. Foxon
Keyword(s):  
Quantum Well ◽  
Valence Band ◽  
Pressure Dependence ◽  
Quantum Well Structures ◽  
Valence Band Discontinuity

The pressure dependence of the valence band discontinuity in quantum well structures

1990 ◽  
Vol 3 (1-6) ◽  
pp. 57-59 ◽  
Author(s):  
V. A. Wilkinson ◽  
J. D. Lambkin ◽  
A. D. Prins ◽  
D. J. Dunstan
Keyword(s):  
Quantum Well ◽  
Valence Band ◽  
Pressure Dependence ◽  
Quantum Well Structures ◽  
Valence Band Discontinuity

scholarly journals Al Composition Dependence of Band Offsets for SiO2 on α-(AlxGa1-x)2O3

2021 ◽  
Author(s):  
Xinyi Xia ◽  
Chaker Fares ◽  
Fan Ren ◽  
Anna Hassa ◽  
Holger von Wenckstern ◽  
...  
Keyword(s):  
Valence Band ◽  
Photoelectron Spectroscopy ◽  
Composition Dependence ◽  
Atomic Layer ◽  
Wide Bandgap ◽  
Band Alignment ◽  
Band Offsets ◽  
Layer Deposition ◽  
Semiconductor System ◽  
Band Alignments

Abstract Valence band offsets were measured by X Ray Photoelectron Spectroscopy for SiO2 deposited by Atomic Layer Deposition on α-(AlxGa1-x)2O3 alloys with x= 0.26-0.74 grown with a continuous composition spread to enable investigations of the band alignment as a function of the alloy composition. From measurement of the core levels in the alloys, the bandgaps were determined to range from 5.8 eV (x=0.26) to 7eV (x=0.74). The valence band offsets were -1.2 eV for x=0.26, -0.2 eV for x=0.42, 0.2 eV for x=0.58 and 0.4 eV for x=0.74. Given the bandgap of the SiO2 was 8.7 eV, this led to conduction band offsets of 4.1 eV (x=0.26) to 1.3 eV (x=0.74). The band alignments were nested for x>0.5 , but at lower Al contents the conductions band offsets were negative, with a staggered band alignment. This shows the challenge of finding appropriate dielectrics for this ultra-wide bandgap semiconductor system.

Direct Optical Measurement of the valence band offset of p+ Si1−x−yGexCy/p− Si (100) by Heterojunction Internal Photoemission

1998 ◽  
Vol 533 ◽  
Author(s):  
C. L. Chang ◽  
L. P. Rokhinson ◽  
J. C. Sturm
Keyword(s):  
Valence Band ◽  
Optical Measurement ◽  
Chemical Vapor ◽  
Band Alignment ◽  
Band Offset ◽  
Valence Band Offset ◽  
Strained Si ◽  
Internal Photoemission ◽  
Capacitance Voltage ◽  
Absorption Measurements

AbstractOptical absorption measurements have been performed to study the effect of carbon on the valence band offset of compressively strained p+ Si1−x−yGexCy/(100) p− Si heterojunction internal photoemission structures grown by Rapid Thermal Chemical Vapor Deposition (RTCVD) with substitutional carbon levels up to 2.5%. Results indicated that carbon decreased the valence band offset by 26 ± 1 meV/ %C. Results from optical measurement in this study agreed with previous data from capacitance-voltage measurements. Based on previous reports of carbon effect on the bandgap of compressively strained Si1−x−yGexCy, our work suggests that the effect of carbon incorporation on the band alignment of Si1−x−yGexCy/Si is to reduce the valence band offset, with a negligible effect on the conduction band alignment.

Sign in / Sign up

Export Citation Format

Share Document