Blueshift in sulfur treated GaAsP/AlGaAs near surface quantum well

Abstract

Comparative study on passivation of GaAs 0.86 P 0.14 / Al 0.6 Ga 0.4 As near-surface quantum well Photoreflectance and photoluminescence spectroscopy of the lattice-matched InGaAs/InAlAs single quantum well J. Appl. Phys. 92, 920 (2002); 10.1063/1.1487906Photoluminescence and photo-modulated reflectance spectra of ion-implanted GaAs/AlGaAs coupled quantum wells Large blueshift was observed in a near-surface GaAs 0.86 P 0.14 /Al 0.7 Ga 0.3 As quantum well upon treatment with Na 2 SÁxH 2 O solution. Very slow etching with simultaneous surface passivation of the quantum well was obtained using this chemical treatment. Photoreflectance (PR) spectra exhibit maximum blueshift of 28 meV after treating the quantum well surface with Na 2 SÁxH 2 O solution for 30 min (top layer thickness reduced to 10 Å ). The blueshift is attributed to an increase in the confinement and/or an image charge effect due to the penetration of the wave function into vacuum. The blueshift is accompanied by a significant reduction in the broadening parameter of the observed e 1 -lh 1 transition in PR spectra indicating effective passivation along with an increase in the confinement.

Band alignment and quantum states of InAs P1−/InP surface quantum wells investigated from ultraviolet photoelectron spectroscopy and photoluminescence

“…The experimental transition energy of SQWs is estimated from theoretical calculations based on envelopefunction formalism. The details of the theoretical modeling have been described elsewhere [12]. The experimental values of e 1 -hh 1 match well with the theoretical calculated values while using a 3.6 eV potential barrier and are listed in Table 1.…”

Effect of light-hole tunnelling on the excitonic properties of GaAsP/AlGaAs near-surface quantum wells

“…The presence of FKOs above the ground state transitions of the NSQW is masked by the coexistence of excited state features in the same energy range. Furthermore, the surface electric field is also estimated via the surface band bending measured by x-ray photoelectron spectroscopy (XPS) [8]. The XPS results also indicate the values of the built-in electric field of ∼ 40 kV cm −1 on the surface of GaAsP/AlGaAs NSQW samples.…”

“…To calculate the energy levels and transition energies of a 10.6 nm thick GaAsP/AlGaAs QW, the envelop function approximation was applied to solve the Schrödinger equation for a finite square potential well using the finite difference method. The details of our theoretical modelling are described elsewhere [8]. The effect of strain in modifying the band structure was also taken into account in the calculation.…”

“…Detailed work on carrier recombination in GaAs 0.86 P 0.14 /Al 0.7 Ga 0.3 As QW and the effect of surface states on the carrier dynamics are not available in the literature. In our earlier works, we studied the effect of the surface electric field and surface band bending on the optical properties of the GaAs 0.86 P 0.14 /Al 0.7 Ga 0.3 As near-surface quantum well (NSQW) [8,9]. In this report, we present a detailed study on the effect of surface states on the exciton formation dynamics of these structures by varying the top barrier layer thickness.…”