Quantum dielectric Theory (QDT) is used to explain the band gap bowing effect observed in III-V-Bismides such as InSb1-xBix, InAs1-xBix, InP1-xBix, GaSb1-xBix, GaAs1-xBix and GaP1-xBix. The dependence of the direct E0 band gap for these alloys on Bi mole fraction is calculated using QDT which requires the evaluation of the bowing parameter c. The bowing parameter gives the deviation of the direct E0 band gap from the linear relationship of E0 with Bi mole fraction. The band gap reduction values obtained using QDT are compared with those calculated using Virtual Crystal approximation (VCA) and Valence Band Anticrossing (VBAC) model as well as with the reported experimental data and the results of the comparison shows excellent agreement. © 2015 Elsevier B.V. All rights reserved.

D P SAMAJDAR

S DHAR

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Physica B: Condensed Matter

Broadband THz radiation emission from photoexcited GaSb1-xBix (0 &lt; x &lt; 1.65%) was investigated. We observed an enhancement in the THz emission with Bi incorporation in GaSb. GaSb1-xBix alloy with showed an emission amplitude comparable to that from LT-GaAs, which is over an order of magnitude higher compared to GaSb. Transient photocurrents due to p-type surface band bending was found to be the dominant emission mechanism in these alloys. Strengthening of the surface field due to Bi induced p-doping is responsible for the observed enhancement. The NIR pump incident angle and THz detection angle study suggests that the photocarrier momentum is preferentially aligned along the refracted excitation beam direction inside the semiconductor alloy. GaSb1-xBix emitter showed better spectral performance compared to a commercially available photoconductive antenna in a THz time domain spectroscopy system. This demonstrates the application potential of this material in THz spectroscopy. © 2018 IOP Publishing Ltd.

Journal of Physics D: Applied Physics

Enhanced terahertz emission from Bi incorporated GaSb

Valence band anticrossing (VBAC) model has been used to explain the strong reduction in band gap as well as the increase in spin-orbit splitting energy with increasing bismuth incorporation in InAs 1- x Bi x , InSb 1 - x Bi x and InP 1- x Bi x . This effect is shown to be due to the restructuring of the valence band as a result of the anticrossing interaction of the extended states of the valence band of the host semiconductor with the Bi related impurity states. The anticrossing interaction causes the splitting of the light hole (LH), heavy hole (HH) and spin-orbit split-off (SO) bands into E + and E - sub bands. The upward movement of the LH/HH and SO E + energy level is responsible for the reduction in bandgap and increase in spin-orbit splitting energy in bismides. The calculated values of the band gap reduction show good agreement with available experimental results. Band dispersion relations for these bismides in the Λ, Δ, and Σ directions are also calculated using the k.p method. © 2015 Elsevier B.V. All rights reserved.

Computational Materials Science

Calculation of Valence Band Structure and Band Dispersion in Indium containing III-V Bismides by k.p method

The reduction in band gap as well as the increase in spin-orbit splitting energy in GaSb1-xBix and GaP1-xBix are explained by the Valence Band Anticrossing (VBAC) model. This restructuring of the valence band is due to the interaction of the Bi related impurity levels with the extended states of the valence band of the host semiconductor. The band gap reduction in GaSb1-xBix and GaP1-xBix calculated using VBAC model are respectively 40.2 meV and 206 meV/at% Bi. A comparison of the theoretical and experimentally obtained values of band gap in GaSbBi shows good agreement. Valence band structure for GaPBi is obtained by the extrapolation of the parameters used for modeling of the GaSbBi system. The upward movement of the spin-orbit split-off E+ energy level in GaSbBi by 19.2 meV/at% Bi is also responsible for the suppression of Auger recombination processes making it a potential candidate for near and mid-infrared optoelectronic applications. © 2015 Elsevier Ltd. All rights reserved.

Materials Science in Semiconductor Processing

Valence band anticrossing model for GaSb1-xBix and GaP1-xBix using k.p method

InP1-xBix epilayers (x?=1.2%) on InP (001) are grown reproducibly by liquid phase epitaxy with conventional solution baking in a H2 environment. The Bi composition and surface morphology of the grown layers are studied by secondary ion mass spectroscopy and atomic force microscopy, respectively. High-resolution x-ray diffraction is used to characterize the lattice parameters and the crystalline quality of the layers. 10K photoluminescence measurements indicate three clearly resolved peaks in undoped InP layers with band-to-band transition at 1.42eV which is redshifted with Bi incorporation in the layer with a maximum band gap reduction of 50meV/% Bi. The effect is attributed to the interaction between the valence band edge and Bi-related defect states as is explained here by valence-band anticrossing model. Room temperature Hall measurements indicate that the mobility of the layer is not significantly affected for Bi concentration up to 1.2%. © 2014 AIP Publishing LLC.

Fulltext

Journal of Applied Physics

The effect of Bi composition on the properties of InP1-xBi x grown by liquid phase epitaxy

The effect of post-growth anneal on the photoluminescence (PL) properties of GaSbBi layers, grown by liquid phase epitaxy, is investigated. It is observed that annealing for temperatures up to 650 °C increases the PL intensity and decreases the PL peak width indicating an improvement in the crystalline quality of the layer. A second peak at 0.72 eV, observed in GaSbBi only, is totally removed by annealing, suggesting that the peak is related to emission from Bi-related antisite defects. A red shift of up to 9 meV is also observed for the band edge emission peak as a result of anneal. © 2014 IOP Publishing Ltd.

Semiconductor Science and Technology

Effect of post-growth anneal on the photoluminescence properties of GaSbBi

We report on the results of optical absorption and Raman spectroscopy measurements on InSbBi layers grown by liquid phase technique. A maximum Bi content of 0.4 at.%, as measured by energy dispersive X-ray (EDX) technique, is used in the experiments. Optical absorption measurements made on the samples indicate a room temperature energy band gap reduction up to about 6 meV with respect to undoped InSb layers grown by the same technique. Bi content calculated from this band gap reduction agrees with that obtained from EDX. A weak peak obtained at 152 cm -1 in the Raman spectrum of the material is identified with the longitudinal optical phonon mode of InBi. Further a mode at 140 cm -1 is observed due to isolated Bi atoms at the interstitial sites. © 2012 Elsevier B.V. All rights reserved.

Journal	Data powered by TypesetPhysica B: Condensed Matter
Publisher	Data powered by TypesetElsevier
ISSN	0921-4526