In the recent years, InGaN/GaN quantum well (QW) light emitting diodes (LEDs) have gathered much importance through the introduction of white LEDs and dual wavelength LEDs. However, the continuous tunability of InGaN/GaN QW LEDs has not been well addressed or discussed. In this paper, we introduce the tunability of an InGaN/GaN QW LED having a well width of 4 nm and In mole fraction of 0.3. The results, obtained from self-consistent solutions of the Schrödinger and Poisson equations, show that the transition energy of the LED may be continuously tuned by the device current. A prominent nonlinearity of the transition energy with the device current is generated, which should be of interest to the research workers in the field of optoelectronics. © 2013 AIP Publishing LLC.

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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

Tunability of InGaN/GaN quantum well light emitting diodes through current

Journal of Applied Physics

The strong piezoelectric field in the InxGa1-xN/GaN quantum well (QW) LEDs, separates the electrons and holes spatially, which decreases the luminescence. Various shapes and compositions of such QWs are studied to improve the performance. We have studied the transition energy (TE), overlap of electron and hole wave functions, band structures and field distributions of the parabolic QWs (PQW) through the self consistent solutions of Schrodinger and Poisson equations. The shape of the PQW is varied along with the compositions and dopings. The square of the overlap of electron and hole wave functions i.e. the transition probability (TP) is strikingly increased, compared to the rectangular QW and it is even higher than the symmetrically staggered QW. At a particular current density, for the same TE, the TP of the PQW increases more than two times that of the rectangular QWs. An important feature, desirable for the QW LEDs emerge. The change of the TE with increase in the current density is minimized. A brief theory, computational procedures and the results will be presented in details with suitable discussions.

Optical and Quantum Electronics

The electron-hole overlap in the parabolic quantum well light emitting diode is much superior to the rectangular: even to that of a staggered quantum well

Although that the continuous tunability of InGaN/GaN QW LEDs, carries the promise of a significant impact in optoelectronics, the reduction of the square of the overlap of electron and hole wave functions (Meh 2) in InGaN/GaN QW LEDs, under certain conditions, is a sizable problem, difficult to overcome. Theoretical investigations have been carried out on the incorporation of Indium (In) in the GaN barrier layers, with an aim of increasing the overlap of electron and hole wave functions. Rigorous studies through the self consistent solution of Schrödinger and Poison equations expose some new and striking results. With suitable doping, the inclusion of In in the barriers can increase Meh 2 to more than two times that of a conventional InGaN/GaN QW LED. In in the barrier along with doping may be suitably utilized to tailor the transition energy and Meh 2 with current density, as desired. The transition energy and the Meh 2 may be made to have a positive or a negative slope with current density or they may be made fairly constant. This paper will outline the theoretical details, computational methodologies, the parameters used, and the striking new results with suitable depictions and discussions. These new information ought to be interesting for current optoelectronics. © 2017 Elsevier B.V.

Photonics and Nanostructures - Fundamentals and Applications

Inclusion of Indium, with doping in the barriers of InxGa1-xN/InyGa1-yN quantum wells reveals striking modifications of the emission properties with current for better operation of LEDs

The near-infrared spectral region is being used for various fields of applications. Near infrared emitters based on InGaN-ZnSnN2 material systems have not been proposed yet. In this paper, a novel type-II InGaN-ZnSnN2/GaN quantum well (QW) light emitting diode structure is presented for the near-infrared emission. Computations are based on the self-consistent solutions of Schrödinger and Poison equations. In the proposed structure, the emission wavelength (λ) and the overlap of electron and hole wave functions (Meh) are studied with current densities, for different dopings, compositions and well widths of the structure. It is found that the Meh and the radiative efficiency are more than 30% and 40% respectively. The large overlap of electron and hole wavefunctions should make QW light emitting diodes in the near infrared range based on these structures feasible. © 2018 Elsevier B.V.

Optical Materials

Near-infrared light emitting diodes based on the type-II InGaN-ZnSnN2/GaN quantum wells

White light emitting diodes (LEDs), dual wavelength LEDs and continuously tunable LEDs have made, InGaN/GaN quantum well (QW) LEDs much important. Infrared emission from InGaN/GaN QW LEDs has not been well addressed or discussed. In this paper, we introduce a tunable InGaN-ZnSnN2/GaN QW LED, emitting in the infrared range, for optical communications. The results are obtained from the self consistent solutions of the Schrödinger and Poisson equations. The tunability of the emission wavelength is in the second optical window of the optical fiber. The device may be directly modulated through the current, for fiber optic communications and may be used to generate a large number of optical carrier frequencies, within the second optical window, suitable for WDM and DWDM. This seems to be one of the first reports on infrared from the nitride QW LEDs. © 2018 Elsevier GmbH

Optik

A tunable LED based on InGaN-ZnSnN2/GaN QW in the infrared range, for optical communications

Applications of multispectral sources are numerous. The previous forms of optical sources are continuously being replaced by efficient LEDs with an emphasis on III-nitrides, since it covers a very wide optical range. In this paper, we are proposing a multispectral linear optical sweep source, based on tunable InGaN/GaN QW LEDs. For linearization, a λ verses current curve of tunable InGaN/GaN QW LED, as obtained from our well established method of solution of Schrödinger and Poisson equations is considered as a model. The entire process of linearization is outlined in a simple form, for clear understanding. The linear sweep is so designed that it can be stopped at any λ,. i.e. color. Changing of the range of the spectral sweep through changes in the device parameters is pointed out. Procedures, necessary constituents and results are presented with suitable discussions. The multispectral ramp should be of much use for a wide range of applications. © 2018 Elsevier GmbH

A multispectral linear optical sweep source, based on tunable InGaN/GaN QW LEDs

Band lineup is one of the most important parameters associated with carrier confinement in heterostructures. Relations for computing the band lineups of Inx Ga1-x N based heterostructures have been developed. The band positions for Inx Ga1-x N/GaN heterointerfaces are calculated from the equations developed, which directly corelate the positions of the bands with the band gap of InN and strain at the interface. The strains are calculated from the In mole fractions and lattice constants. The parameters implicitly involved are the elastic stiffness constants (C11 and C12), the hydrostatic deformation potential of the conduction band (a′), and the hydrostatic deformation potential (a) and shear deformation potential (b) for the valence band. Computations have been carried out for different reported band gaps of InN. The effects of strain become prominent as the mole fraction of In increases, changing the band offset ratio. © 2009 American Institute of Physics.

Journal	Journal of Applied Physics
Publisher	AMER INST PHYSICS
ISSN	0021-8979