Optical properties of an InGaAs-InP interdiffused quantum well

Abstract

A comprehensive model is developed for the calculation of polarization-dependent absorption coefficients and refractive index of the InGaAs-InP interdiffused multiple-quantumwell at room temperature for wavelengths ranging from 1.1 to 2.4 m. Groups III and V types of interdiffusion are considered separately. The as-grown structure is a latticed-matched In0:53Ga0:47As-InP structure with a well width of 60Å. The optical transitions consist of a full quantum-well calculation together with 0; X; and L valleys contributions and through the Kramers-Krönig transformation to link the real and imaginary parts of the dielectric functions. The results show that Group-III-only interdiffusion produces compressive strain and results in a band-edge red shift and refractive index enlargement, while the tensile strain induced by Group-V-only interdiffusion results in a vice verse effect. This provides a left and right tunable band edge and positive and negative index steps dependent on the interdiffusion process. A small and constant birefringence of 0.005 at around 1.55 m can also be obtained over a 50-nm wavelength range by using Group-V-only interdiffusion. These properties have strong implications in realizing a tunable and high-performance device as well as for photonic integrations.

Envelope Function Approximation (EFA) Bandstructure Calculations for III-V Non-square Stepped Alloy Quantum Wells Incorporating Ultra-narrow (~5Å) Epitaxial Layers

“…Similar anomalous behaviour has been reported for narrow ($25Ð) InGaAs-InGaAsP square quantum well structures using a 2-band (HH/LH) EFA model when the symmetrised boundary conditions are applied across the hetero-interfaces[31]. We note here that the HH/LH and HH/LH/SO models are among the most widely used for the description of quantum well electronic states (see for example[35][36][37][38][39]). One of the reasons for the widespread use of these models is that, unlike the case where the conduction band is included, spurious solutions are avoided entirely.…”

Asymmetric double quantum wells with smoothed interfaces

“…The wave functions and energy states of ADQWs were derived and analyzed in their changes: due to the different mutual widths of coupled wells, for different degree of the broadening, and under increasing external electric field. Our calculations, however, are simulating the behavior of diffused electroabsorptive light modulators [17,18] and the lightemitter regions of some types of quantum cascade lasers [54].…”

“…Here, once more, we may see an anticrossing situation caused by bias for the levels n = 0 and n = 1 around the 2-3 meV/nm region of electric field strength. Investigating structure may work as an electroabsorptive light modulator [17,18] or as an active stimulated emission region in the far/mid-infrared quantum cascade (QC) lasers [54]. The schematic for this laser operation [4] shown at Fig.…”

“…The inter-diffused QW structures such as GaAs/AlGaAs [16] and InP/InGaAs [17,18] have been actively investigated for improved inter-sub-band electro-absorptive light modulation [17,18], and widely used in several optical devices, such as electro-absorptive [19] and lateral confinement [20] waveguides, light modulators [21,22], and wavelength tunable lasers [10,11]. The improved quantum confinement and a higher tunneling rate achieved in the inter-diffused QW's cannot be fulfilled by a rectangular QW structure simultaneously.…”

Direct writing of multiple-wavelength chip in InGaAs-InGaAsP structure using pulsed laser irradiation

“…Figure 2 shows the calculated excitonic peak shift with respect to the diffusion length of the QW that characterizes the degree of intermixing in the QW. The plot is generated from a series of bound states calculation of electron and holes confined in the QW using Ben-Daniel Duke's equation in the effective mass approximation [6]. As shown in Figure 2, the QW confinement becomes weak for a diffusion length of 55 Å, which might result in a broader PL spectrum as observed in Figure 1(b).…”