A mathematical model based on the one dimensional diffusive transport of bismuth atoms has been used to study the concentration profile of the bismuth atoms during the liquid phase epitaxial growth of InPBi. This model is used to determine the growth kinetics at equally spaced layers in the proximity of the grown epitaxial interface. Various growth parameters such as growth temperature, melt supercooling and the continuous cooling ramp applied during growth have been optimized to find out the suitable conditions of growth. The thickness of the epitaxial layers as a function time is also estimated. Valence Band anticrossing (VBAC) model is used to determine the reduction in band gap and increase in spin-orbit splitting energy for InP1−xBix. The valence band structure of InPBi is modified due to the interaction of the Bi related impurity levels with the light hole (LH), heavy hole (HH) and spin-orbit split-off (SO) sub bands. A 12 × 12 Hamiltonian is solved to find out the valence band structure of InPBi in the <100> direction. © Springer International Publishing Switzerland 2017.

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T D DAS

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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

Effect of Bismuth Incorporation on the Growth Kinetics and Valence Band Structure for InP 1−x Bi x Grown Using Liquid Phase Epitaxy

Springer Proceedings in Physics

Valence Band Anticrossing (VBAC) Model is used to calculate the changes in band structure of Bi containing alloys such as InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix due to the incorporation of dilute concentrations of bismuth. The coupling parameter CBi which gives the magnitude of interaction of Bi impurity states with the LH, HH and SO sub bands in VBAC depends on the increase in the HH/LH related energy level EHH/LH+, location of the Bi related impurity level EBi and valence band offset ΔEVBM between the endpoint compounds in the corresponding III-V-Bi. The reduction in band gap as well as the enhancement of the spin-orbit splitting energy is well explained using this model and the calculated results are compared with the results of Virtual Crystal Approximation (VCA) and Density Functional Theory (DFT) calculations, as well as with the available experimental data and are found to have good agreement. The incorporation of Bi mainly perturbs the valence band due to the interaction of the Bi impurity states with the HH, LH and SO bands. The lowering of the conduction band minimum (CBM) due to VCA is added with the upward movement of the HH/LH bands to get the total reduction in band gap for the bismides. The valence band shifts of 31.9, 32.5, 20.8 and 12.4 meV/at%Bi for InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix respectively constitute 65, 76, 59 and 31% of the total band gap reduction and the rest is the contribution of the conduction band shift. The spin-orbit splitting energy also shows significant increase with the maximum change in InPBi and the minimum in InSbBi. The same is true for Ga containing bismides if we make a comparison with the available values for GaAsBi and GaPBi with that of GaSbBi. It has also been observed that the increase in splitting energy is greater in case of the bismides such as InAsBi, InPBi and GaAsBi than the bismides such as InSbBi and GaSbBi with the parent substrates having higher values of splitting energy. This may be due to the proximity of the Bi related impurity level EBi with the SO bands of InAs, InP and GaAs. © 2015 Elsevier Ltd. All rights reserved.

Superlattices and Microstructures

Influence of Bi-related impurity states on the bandgap and spin-orbit splitting energy of dilute III-V-Bi alloys: InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix

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

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 valence band anticrossing model has been used to calculate the heavy/light hole and spin-orbit split-off energies in InAs1-xBix and InSb1-xBix alloy systems. It is found that both the heavy/light hole, and spin-orbit split E+ levels move upwards in energy with an increase in Bi content in the alloy, whereas the split E- energy for the holes shows a reverse trend. The model is also used to calculate the reduction of band gap energy with an increase in Bi mole fraction. The calculated values of band gap variation agree well with the available experimental data.

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ISSN	0930-8989