Beşire Gönül

Supersymmetric approach to exactly solvable systems with position-dependent effective masses

We discuss the relationship between exact solvability of the Schrodinger equation with a position-dependent mass and the ordering ambiguity in the Hamiltonian operator within the framework of supersymmetric quantum mechanics. The one-dimensional Schrodinger equation, derived from the general form of the effective mass Hamiltonian, is solved exactly for a system with exponentially changing mass in the presence of a potential with similar behaviour, and the corresponding supersymmetric partner Hamiltonians are related to the effective-mass Hamiltonians proposed in the literature.

An alternative treatment for Yukawa-type potentials

We propose here a new approximation scheme to obtain analytic expressions for the bound state energies and eigenfunctions of Yukawa-like potentials. The predicted energies are in excellent agreement with the accurate numerical values reported in the literature.

Comparison of the band alignment of strained and strain-compensated GaInNAs QWs on GaAs and InP substrates

We present a comparison of the band alignment of the Ga1−xInxNyAs1−y active layers on GaAs and InP substrates in the case of conventionally strained and strain-compensated quantum wells. Our calculated results present that the band alignment of the tensile-strained Ga1−xInxNyAs1−y quantum wells on InP substrates is better than than that of the compressively strained Ga1−xInxNyAs1−y quantum wells on GaAs substrates and both substrates provide deeper conduction wells. Therefore, tensile-strained Ga1−xInxNyAs1−y quantum wells with In concentrations of x⩽0.53 on InP substrates can be used safely from the band alignment point of view when TM polarisation is required. Our calculated results also confirm that strain compensation can be used to balance the strain in the well material and it improves especially the band alignment of dilute nitride Ga1−xInxNyAs1−y active layers on GaAs substrates. Our calculations enlighten the intrinsic superiority of N-based lasers and offer the conventionally strained and strain-compensated Ga1−xInxNyAs1−y laser system on GaAs and InP substrates as ideal candidates for high temperature operation.

Analysis of the band alignment of highly strained indium-rich GaInNAs QWs on InP substrates

The focus of this paper is to present the calculations of the band alignment of indium-rich (>53%) highly strained Ga1−xInxNyAs1−y quantum wells on InP substrates which allows an emission wavelength of the order of 2.3 µm. We concentrate on the band alignment of Ga0.22In0.78N0.01As0.99 wells lattice matched to In0.52Al0.48As barriers. Our calculations show that the incorporation of nitrogen into Ga1−xInxAs improves the band alignment significantly allowing Ga0.22In0.78N0.01As0.99/In0.52Al0.48As quantum wells on InP substrates to compete with the unique band alignment of GaInNAs/GaAs quantum wells on GaAs substrates.

Achieving carrier and photon confinement in Ga(NAsP)/AlGaP/GaP QWs on Si substrates

A detailed comparative theoretical analysis on both carrier and photon confinement of dilute nitride direct bandgap GaN

EXACT SOLUTIONS OF EFFECTIVE-MASS SCHRÖDINGER EQUATIONS

_{x}

Critical layer thickness of GaIn(N)As(Sb) QWs on GaAs and InP substrates for (001) and (111) orientations

As

Comparative study of the band-offset ratio of conventionally strained and strain-compensated InGaAs/GaAs QW lasers

_{1-x-y}

The comparison of the band alignment of GaInAsN quantum wells on GaAs and InP substrates for (0 0 1) and (1 1 1) orientations

P

Revealing the effects of nitrogen on threshold current density in GaNxAsyP1−x−y/GaP/AlzGa1−zP type I QW laser structures by hydrostatic pressure

_{y}