Direct gap Group IV semiconductors for next generation Si-based IR photonics

2014 ◽  
Vol 1666 ◽  
Author(s):  
John Kouvetakis ◽  
James Gallagher ◽  
José Menéndez
Keyword(s):  
Band Gap ◽  
Lattice Parameter ◽  
Group Iv ◽  
Optical Data ◽  
Long Wavelength ◽  
Group Iv Semiconductors ◽  
Wide Range ◽  
Direct Band ◽  
Ternary Semiconductor ◽  
Group Iv Elements

ABSTRACTThis paper presents synthesis and optical properties of mono-crystalline Ge1-ySny and Ge1-x-ySixSny semiconductor alloys grown on Si/Ge platforms via purposely designed CVD routes using highly reactive Si/Ge/Sn hydrides including Ge3H8, Ge4H10, Si4H10 and SnD4. The Ge1-ySny materials are shown to exhibit strong and tunable photoluminescence induced by the substitution of sizable Sn concentrations in the Ge diamond lattice ultimately leading to an indirect-to-direct band gap crossover at y= 0.08-0.09. The optical data indicate that the IR coverage of the alloy extends well beyond that of elemental Ge into the broader long wavelength range suggesting a variety of applications in Si-based photonics. Ge1-x-ySixSny alloys represent the first viable ternary semiconductor among group IV elements with independently tunable lattice parameter and electronic structure. Studies of the compositional dependence of direct and indirect edges in these alloys using photoluminescence and photocurrent measurements are reviewed. The optical results show band gap variation over a wide range above and below that of Ge from 1.1 to 0.5 eV and provide the first demonstration of direct gap behavior in this semiconductor system.

Sn-based Group-IV Semiconductors on Si: New Infrared Materials and New Templates for Mismatched Epitaxy

2005 ◽  
Vol 891 ◽  
Author(s):  
John Tolle ◽  
Radek Roucka ◽  
Vijay D'Costa ◽  
Jose Menendez ◽  
Andrew Chizmeshya ◽  
...  
Keyword(s):  
Band Gap ◽  
Buffer Layer ◽  
Lattice Mismatch ◽  
Group Iv ◽  
Buffer Layers ◽  
Direct Band Gap ◽  
Group Iv Semiconductors ◽  
Direct Band ◽  
Infrared Materials ◽  
Edge Dislocations

ABSTRACTWe report growth and properties of GeSn and SiGeSn alloys on Si (100). These materials are prepared using a novel CVD approach based on reactions of Si-Ge hydrides and SnD4. High quality GeSn films with Sn contents up to 20%, and strain free microstructures have been obtained. The lattice mismatch between the films and Si is relieved by Lomer edge dislocations located at the interface. This material is of interest due to the predicted cross-over to a direct gap semiconductor for moderate Sn concentrations. We find that the direct band gap, and, consequently, the main absorption edge, shifts monotonically to lower energies as the Sn concentration is increased. The compositional dependence of the direct band gap shows a strong bowing, such that the direct band gap is reduced to 0.4 eV (from 0.8 eV for pure Ge) for a concentration of 14% Sn. The ternary SiGeSn alloy has been grown for the first time on GeSn buffer layers. This material opens up entirely new opportunities for strain and band gap engineering using group-IV materials via decoupling of strain and composition. Our SiGeSn layers have lattice constants above and below that of pure Ge, and depending on the thickness and composition of the underlying buffer layer they can be grown relaxed, with compressive, or with tensile strain. In addition to acting as a buffer layer for the growth of SiGeSn, we have found that GeSn can act as a template for the subsequent growth of a variety of materials, including III-V semiconductors.

scholarly journals The Band-Gap Studies of Short-Period CdO/MgO Superlattices

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Ewa Przeździecka ◽  
P. Strąk ◽  
A. Wierzbicka ◽  
A. Adhikari ◽  
A. Lysak ◽  
...  
Keyword(s):  
Band Gap ◽  
Layer Thickness ◽  
Energy Gap ◽  
Band Gaps ◽  
Short Period ◽  
Wide Range ◽  
Salt Structure ◽  
Short Period Superlattices ◽  
Direct Band ◽  
Sublayer Thickness

AbstractTrends in the behavior of band gaps in short-period superlattices (SLs) composed of CdO and MgO layers were analyzed experimentally and theoretically for several thicknesses of CdO sublayers. The optical properties of the SLs were investigated by means of transmittance measurements at room temperature in the wavelength range 200–700 nm. The direct band gap of {CdO/MgO} SLs were tuned from 2.6 to 6 eV by varying the thickness of CdO from 1 to 12 monolayers while maintaining the same MgO layer thickness of 4 monolayers. Obtained values of direct and indirect band gaps are higher than those theoretically calculated by an ab initio method, but follow the same trend. X-ray measurements confirmed the presence of a rock salt structure in the SLs. Two oriented structures (111 and 100) grown on c- and r-oriented sapphire substrates were obtained. The measured lattice parameters increase with CdO layer thickness, and the experimental data are in agreement with the calculated results. This new kind of SL structure may be suitable for use in visible, UV and deep UV optoelectronics, especially because the energy gap can be precisely controlled over a wide range by modulating the sublayer thickness in the superlattices.

scholarly journals First principles calculations on theoretical band gap improvement of IIIA-VA zinc-blende semiconductor InAs

2020 ◽  
Vol 31 (12) ◽  
pp. 2050178
Author(s):  
Waqas Mahmood ◽  
Arfan Bukhtiar ◽  
Muhammad Haroon ◽  
Bing Dong
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Local Density ◽  
Lattice Parameter ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Zinc Blende ◽  
Valence States ◽  
Direct Band ◽  
Experimental Findings

The structural, electronic, dielectric and vibrational properties of zinc-blende (ZB) InAs were studied within the framework of density functional theory (DFT) by employing local density approximation and norm-conserving pseudopotentials. The optimal lattice parameter, direct band gap, static dielectric constant, phonon frequencies and Born effective charges calculated by treating In-4d electrons as valence states are in satisfactory agreement with other reported theoretical and experimental findings. The calculated band gap is reasonably accurate and improved in comparison to other findings. This work will be useful for more computational studies related to semiconductor devices.

Ternary GeSiSn alloys: New opportunities for strain and band gap engineering using group-IV semiconductors

2010 ◽  
Vol 518 (9) ◽  
pp. 2531-2537 ◽  
Author(s):  
V.R. D'Costa ◽  
Y.-Y. Fang ◽  
J. Tolle ◽  
J. Kouvetakis ◽  
J. Menéndez
Keyword(s):  
Band Gap ◽  
Group Iv ◽  
Band Gap Engineering ◽  
Group Iv Semiconductors

Composition-dependent band gaps and indirect–direct band gap transitions of group-IV semiconductor alloys

2015 ◽  
Vol 17 (33) ◽  
pp. 21605-21610 ◽  
Author(s):  
Zhen Zhu ◽  
Jiamin Xiao ◽  
Haibin Sun ◽  
Yue Hu ◽  
Ronggen Cao ◽  
...  
Keyword(s):  
Band Gap ◽  
Transition Point ◽  
Reliable Method ◽  
Group Iv ◽  
Band Gaps ◽  
Semiconductor Alloys ◽  
Direct Band Gap ◽  
Group Iv Semiconductor ◽  
Direct Band

Obtaining the value of the band gap and the composition of an indirect–direct band gap transition point for group-IV semiconductor alloys by an efficient and reliable method.

scholarly journals Towards a direct band gap group IV Ge-based material

2019 ◽  
Vol 92 ◽  
pp. 39-46 ◽  
Author(s):  
Tuan T. Tran ◽  
Jay Mathews ◽  
J.S. Williams
Keyword(s):  
Band Gap ◽  
Group Iv ◽  
Direct Band Gap ◽  
Direct Band

Photoelectrochemical properties of n-type KTaO3 single crystals in alkaline electrolytes

2010 ◽  
Vol 25 (1) ◽  
pp. 52-62 ◽  
Author(s):  
Irene E. Paulauskas ◽  
Gerald E. Jellison ◽  
Lynn A. Boatner
Keyword(s):  
Band Gap ◽  
Single Crystals ◽  
Model Potential ◽  
Water Dissociation ◽  
Transition Metal Atoms ◽  
Wide Range ◽  
Alkaline Electrolytes ◽  
Direct Band ◽  
Indirect Band Gap ◽  
External Quantum Yield

Semiconducting KTaO3 single crystals were investigated as a model potential photoanode for hydrogen production using photoelectrochemical cells. To modify the electronic properties of KTaO3 by reducing the band gap and thereby increasing the absorption of light at longer wavelengths, the crystals were doped during growth. A wide range of dopant elements was used that consisted primarily of transition metal atoms. Most of the crystals exhibited n-type behavior with carrier concentrations from 4 × 1018 to 2.6 × 1020 cm–3. The position of the band edges indicated that the crystals were thermodynamically capable of water dissociation. External quantum yield measurements revealed that the samples were photoactive up to a wavelength of ∼350 nm. The indirect band gap and a parameter denoted as E1 that is related to the direct band edge of the semiconductor, were found to be essentially the same for all of the samples. These results indicate that the various dopants and treatments did not produce changes in the KTaO3 electronic structure that were sufficient to significantly modify the behavior of KTaO3 in a PEC cell.

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