Quantum-well anisotropic forbidden transitions induced by a common-atom interface potential

Abstract

A prominent effect of the interface potential ͑IP͒ ͓E. L. Ivchenko and A. Yu. Kaminski, Phys. Rev. B 54, 5852 ͑1996͒; O. Krebs and P. Voisin, Phys. Rev. Lett. 77, 1829 ͑1996͔͒, the optical anisotropy of the forbidden transitions in quantum wells has been observed by reflectance-difference spectroscopy. Predictions by the heavy-light-hole coupling IP models are qualitatively consistent with all the observed features of the forbidden and the allowed transitions. The fact that the predicted value of the relative transition strength, which depends on neither the IP strength nor the electric field, disagrees with the observed one indicates that coupling involving X and/or L bands may also be important.

Determination of the values of hole-mixing coefficients due to interface and electric field inGaAs/Alx<

“…1͑b͒. Regardless of the divergence in the theoretical models, the hole-mixing Hamiltonian HЈ has the form 3,7,11,14,17,18 HЈϭ ͫ DFϩp ͚ Because the interface potential and the bulk term of electric field have a remarkable distinction from the bulk inversion asymmetries in that the former can generate in-plane anisotropy at kϭ0, so far almost all theoretical investigations are restricted to calculating the anisotropy at kϭ0. But the hole-mixing Hamiltonian is capable of coupling the heavyand light-hole states at k 0, the anisotropy spectra contributed by all points in k space are calculated in our work besides the computation at kϭ0.…”

“…But giant in-plane optical anisotropy have been observed in In x Ga 1Ϫx As/InP, In x Al 1Ϫx As/InP, biased GaAs/ AlAs quantum wells ͑QW's͒, etc., for light propagating along ͓001͔ axis and their existences have been proved by symmetry arguments. [1][2][3][4][5][6][7][8][9] It is found that the lower symmetry (C 2v ) of the chemical bond arrangement for interface atoms can introduce asymmetry in ͓001͔ direction, which will induce anisotropy in ͑001͒ plane. Krebs et al 10 consider that the couplings of the heavy-and light-hole states at the minizone center due to interface and external-potential-inversion asymmetries play a much stronger role in the anisotropy than those due to the classical bulk-inversion asymmetry.…”

“…Recently, the in-plane optical anisotropy ͑on 10 Ϫ4 order͒ of the al-lowed and the forbidden transitions in GaAs/Al x Ga 1Ϫx As and In x Ga 1Ϫx As/GaAs QW's have been observed by reflectance-difference spectroscopy ͑RDS͒. 7,23 RDS is designed to measure the small difference between the normalincidence complex reflectance for two orthogonal directions in the surface plane without rotating the polarizer or the sample. 19 Its resolution can be as high as 10 Ϫ5 .…”

In-plane optical anisotropy of InAs/GaSb superlattices with alternate interfaces

“…Exactly speaking, the IPOA of upper and lower IFs will cancel each other for the SLs with D 2 d symmetry. Although, it is hard to realize such perfect IFs by the growth process that has many uncontrollable factors, the weak IPOA is still well observed by reflectance difference spectroscopy (RDS) [3,4]. For the NCA SLs, it has been observed that the IPOA is very strong [5-8].…”

Observation of strong anisotropic forbidden transitions in (001) InGaAs/GaAs single-quantum well by reflectance-difference spectroscopy and its behavior under uniaxial strain

“…Wang et al has studied forbidden transitions in In x Ga 1- x As/GaAs by photoreflectance (PR) and attributed the forbidden transition to the built-in electric field [12]. Chen et al [1] and Ye et al [6] observed anisotropic forbidden transition in In x Ga 1- x As/GaAs by RDS. Chen ascribed the anisotropic forbidden transition to the interplay of interface C 2 ν symmetry and built-in electric field, while Ye attributed it to both the built-in electric field and segregation effect.…”