Variation in the Properties of Superlattices with Band Offsets

1986 ◽  
Vol 90 ◽  
Author(s):  
T. C. McGill ◽  
R. H. Miles ◽  
G. Y. Wu ◽  
T. J. Watson
Keyword(s):  
Band Gap ◽  
Effective Mass ◽  
Valence Band ◽  
Band Offsets

ABSTRACTThe implications for recent reports of large valence band offsets the HgTe-CdTe heterojunction are examined. The variation of the band gap and effective mass for transport normal to the layers in the superlattice is examined in detail.

Conduction and Valence Band Offsets at the Hydrogenated Amorphous Silicon-Carbon/Crystalline Silicon Interface Via Capacitance Techniques

1993 ◽  
Vol 297 ◽  
Author(s):  
John M. Essick ◽  
Richard T. Mather ◽  
Murray S. Bennett ◽  
James Newton
Keyword(s):  
Amorphous Silicon ◽  
Band Gap ◽  
Valence Band ◽  
Crystalline Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Thick Layer ◽  
Band Offset ◽  
Band Offsets ◽  
Silicon Carbon ◽  
Hydrogenated Amorphous

Heterostructure Schottky diode samples each composed of a sub-micron thick layer of intrinsic hydrogenated amorphous silicon-carbon (a-Si1−xCx:H) deposited on an n-type crystalline silicon (c-Si) substrate are used to measure the a-Si1−xCx:H/c-Si band offsets via junction capacitance techniques. The samples range in carbon concentration from x=0.0−0.3. First, a thermally activated capacitance step due to the response of defects at the amorphous/crystalline interface is evident in capacitance vs. temperature spectra taken on all these samples. The bias-dependence of this step’s activation energy provides a direct measure of the a-Si1−xCx:H/c-Si interface potential as a function of c-Si depletion width in each sample. By application of Poisson’s equation, we find that the a-Si1−xCx:H/c-Si conduction band offset ΔEc. increases from 0.00 to 0.10 eV as x increases from 0.00 to 0.26. Second, while under reverse-bias at low temperature, we optically pulsed each sample with c-Si band-gap light to create trapped holes at the a-Si1−xCx:H/c-Si valence band offset ΔEV. By noting the threshold for the subsequent optical release of these trapped holes by sub-band gap light, we found that ΔEV increases from 0.67 to ≥0.83 eV as x increases from 0.00 to 0.26.

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.

Photoconductivité dans l'alliage GaAsxSb1−x en présence d'un champ magnétique

1974 ◽  
Vol 52 (8) ◽  
pp. 743-747 ◽  
Author(s):  
A. Filion ◽  
E. Fortin
Keyword(s):  
Magnetic Fields ◽  
Band Gap ◽  
Effective Mass ◽  
Alloy Composition ◽  
Longitudinal Optical ◽  
Optical Phonons ◽  
Champ Magnétique

The intrinsic photoconductivity of several samples of the alloy GaAsxSb1−x has been studied at 4.2 K in the presence of magnetic fields of up to 65 kG. Values for the band-gap, the reduced effective mass of the carriers, the energy of the longitudinal optical phonons across the alloy composition are deduced from the measurements.

A Purely Spectroscopic Technique for Determining Energy Band Offsets in Quantum Wells

1991 ◽  
Vol 240 ◽  
Author(s):  
Emil S. Koteies
Keyword(s):  
Quantum Wells ◽  
Valence Band ◽  
Accurate Determination ◽  
Energy Difference ◽  
Spectroscopic Technique ◽  
Band Offsets ◽  
Band Energy ◽  
Semiconductor Quantum Wells ◽  
Sensitive Function

ABSTRACTWe have developed a novel experimental technique for accurately determining band offsets in semiconductor quantum wells (QW). It is based on the fact that the ground state heavy- hole (HH) band energy is more sensitive to the depth of the valence band well than the light-hole (LH) band energy. Further, it is well known that as a function of the well width, Lz, the energy difference between the LH and HH excitons in a lattice matched, unstrained QW system experiences a maximum. Calculations show that the position, and more importantly, the magnitude of this maximum is a sensitive function of the valence band offset, Qy, which determines the depth of the valence band well. By fitting experimentally measured LH-HH splittings as a function of Lz, an accurate determination of band offsets can be derived. We further reduce the experimental uncertainty by plotting LH-HH as a function of HH energy (which is a function of Lz ) rather than Lz itself, since then all of the relevant parameters can be precisely determined from absorption spectroscopy alone. Using this technique, we have derived the conduction band offsets for several material systems and, where a consensus has developed, have obtained values in good agreement with other determinations.

Direct evaluation of hole effective mass of SnS–SnSe solid solutions with ARPES measurement

2021 ◽  
Author(s):  
Issei Suzuki ◽  
Zexin Lin ◽  
Sakiko Kawanishi ◽  
Kiyohisa Tanaka ◽  
Yoshitaro Nose ◽  
...  
Keyword(s):  
Effective Mass ◽  
Valence Band ◽  
Thermoelectric Properties ◽  
Solid Solutions ◽  
Photoemission Spectroscopy ◽  
Direct Evaluation ◽  
Hole Effective Mass ◽  
Single Crystalline ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Effective Masses

Valence band dispersions of single-crystalline SnS1-xSex solid solutions were observed by angle-resolved photoemission spectroscopy (ARPES). The hole effective masses, crucial factors in determining thermoelectric properties, were directly evaluated. They decrease...

Reorganization of the topological surface mode of topological insulating α-Sn

2021 ◽  
Author(s):  
Rui Tan ◽  
Qi Qi ◽  
Peng Wang ◽  
Yan-Qiang Cao ◽  
Rongrong Si ◽  
...  
Keyword(s):  
Band Gap ◽  
Valence Band ◽  
Structure Evolution ◽  
Surface Mode ◽  
Dirac Cone ◽  
Natural Structure ◽  
Topological Phase Transition ◽  
Topological Surface ◽  
Systematic Understanding ◽  
Work First

Abstract α-Sn is a topologically nontrivial semimetal in its natural structure. Upon compressively strained in plane, it transforms into a topological insulator. But, up to now, a clear and systematic understanding of the topological surface mode of topological insulating α-Sn is still lacking. In the present work, first-principle simulations are employed to investigate the electronic structure evolution of Ge1-xSnx alloys aiming at understanding the band reordering, topological phase transition and topological surface mode of α-Sn in detail. Progressing from Ge to Sn with increasing Sn content in Ge1-xSnx, the conduction band inverts with the first valence band and then with the second valence band sequentially, rather than inverting with the latter directly. Correspondingly, a topologically nontrivial surface mode arises in the first inverted band gap. Meanwhile, a fragile Dirac cone appears in the second inverted band gap as a result of the reorganization of the topological surface mode caused by the first valence band. The reorganization of the topological surface mode in α-Sn is very similar to the HgTe case. The findings of the present work are helpful for understanding and utilizing of the topological surface mode of α-Sn.

Effect of Deposition Method on Valence Band Offsets of SiO2 and Al2O3 on (Al0.14Ga0.86)2O3

2018 ◽  
Vol 8 (7) ◽  
pp. Q3001-Q3006 ◽  
Author(s):  
Chaker Fares ◽  
F. Ren ◽  
David C. Hays ◽  
B. P. Gila ◽  
S. J. Pearton
Keyword(s):  
Valence Band ◽  
Deposition Method ◽  
Band Offsets

scholarly journals Defects in SiC for Quantum Computing

MRS Advances ◽  
2019 ◽  
Vol 4 (40) ◽  
pp. 2217-2222
Author(s):  
Renu Choudhary ◽  
Rana Biswas ◽  
Bicai Pan ◽  
Durga Paudyal
Keyword(s):  
Band Gap ◽  
Valence Band ◽  
Density Functional ◽  
Single Photon ◽  
Band Edge ◽  
Valence Band Edge ◽  
Dangling Bonds ◽  
Defect Levels ◽  
Formation Energies ◽  
Qubit Operation

AbstractMany novel materials are being actively considered for quantum information science and for realizing high-performance qubit operation at room temperature. It is known that deep defects in wide-band gap semiconductors can have spin states and long coherence times suitable for qubit operation. We theoretically investigate from ab-initio density functional theory (DFT) that the defect states in the hexagonal silicon carbide (4H-SiC) are potential qubit materials. The DFT supercell calculations were performed with the local-orbital and pseudopotential methods including hybrid exchange-correlation functionals. Di-vacancies in SiC supercells yielded defect levels in the gap consisting of closely spaced doublet just above the valence band edge, and higher levels in the band gap. The divacancy with a spin state of 1 is charge neutral. The divacancy is characterized by C-dangling bonds and a Si-dangling bonds. Jahn-teller distortions and formation energies as a function of the Fermi level and single photon interactions with these defect levels will be discussed. In contrast, the anti-site defects where C, Si are interchanged have high formation energies of 5.4 eV and have just a single shallow defect level close to the valence band edge, with no spin. We will compare results including the defect levels from both the electronic structure approaches.

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