Linear bounded potential model for semiconductor band bending

We propose a simple but unexplored model for the semiconductor band bending with the aim to obtain a relatively simple expression to calculate the energy spectrum for the confined levels and the analytical expressions for wave-functions. This model consists of a linear potential but it is bounded or trimmed in energy unlike the well known wedge potential model. We present exact solutions for this potential in the frame of the effective mass approximation and they are valid for electron or hole confinement potential. This model provides a more adequate physical scenario than the wedge potential since it takes into account the charge balance involved in the band bending potential. These results allow to treat confined potential problems as in the case of a two-dimensional electron gas (2DEG) in a simplified way. We discuss the application of this approximation to the recombination time of electrons an holes and for the Franz-Keldysh effect.

Ab initio study of the effect of 2D layer rippling on the electronic properties of 2D/H-terminated diamond (100) heterostructures

We report an ab initio study of the effect of rippling on the structural and electronic properties of the hexagonal Boron Nitride (hBN) and graphene two-dimensional (2D) layers and heterostructures created by placing these layers on the Hydrogen-terminated (H-) diamond (100) surface. Surprisingly, in graphene, rippling does not open a band gap at the Dirac point but does cause the Dirac cone to be shifted and distorted. For the 2D/H-diamond (100) heterostructures, a combined sampling and a clustering approach were used to find the most favorable alignment of the 2D layers. Heterostructures with rippled layers were found to be the most stable. A larger charge transfer was observed in the heterostructures with rippled hBN (graphene) than their planner counterparts. Band offset analysis indicates a Type-II band alignment for both the wavy and planar heterostructures, with the corrugated structure having stronger hole confinement due to the larger valence band offset between the hBN layer and the H-diamond (100) surface. Graphic abstract

From "weak" to "strong" hole confinement in a Mott insulator

We study the problem of a single hole in an Ising antiferromagnet and, using the magnon expansion and analytical methods, determine the expansion coefficients of its wave function in the magnon basis. In the 1D case, the hole is “weakly” confined in a potential well and the magnon coefficients decay exponentially in the absence of a string potential. This behavior is in sharp contrast to the 2D square lattice where the hole is “strongly” confined by a string potential and the magnon coefficients decay superexponentially. The latter is identified here to be a fingerprint of the strings in doped antiferromagnets that can be recognized in the numerical or cold atom simulations of the 2D doped Hubbard model. Finally, we attribute the differences between the 1D and 2D cases to the magnon-magnon interactions being crucially important in a 1D spin system.

Enhanced Internal Quantum Efficiency of Bandgap-Engineered Green W-Shaped Quantum Well Light-Emitting Diode

To improve the internal quantum efficiency of green light-emitting diodes, we present the numerical design and analysis of bandgap-engineered W-shaped quantum well. The numerical results suggest significant improvement in the internal quantum efficiency of the proposed W-LED. The improvement is associated with significantly improved hole confinement due to the localization of indium in the active region, leading to improved radiative recombination rate. In addition, the proposed device shows reduced defect-assisted Shockley-Read-Hall (SRH) recombination rate as well as Auger recombination rate. Moreover, the efficiency rolloff in the proposed device is associated with increased built-in electromechanical field.