A study of photomodulated reflectance on staircase-like, n-doped GaAs-AlxGa1−xAs quantum well structuresReportar como inadecuado




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Nanoscale Research Letters

, 7:622

International Conference on Superlattices, Nanostructures, and Nanodevices ICSNN 2012

Abstract

In this study, photomodulated reflectance PR technique was employed on two different quantum well infrared photodetector QWIP structures, which consist of n-doped GaAs quantum wells QWs between undoped AlxGa1−xAs barriers with three different x compositions. Therefore, the barrier profile is in the form of a staircase-like barrier. The main difference between the two structures is the doping profile and the doping concentration of the QWs. PR spectra were taken at room temperature using a He-Ne laser as a modulation source and a broadband tungsten halogen lamp as a probe light. The PR spectra were analyzed using Aspnes’ third derivative functional form.

Since the barriers are staircase-like, the structure has different ground state energies; therefore, several optical transitions take place in the spectrum which cannot be resolved in a conventional photoluminescence technique at room temperature. To analyze the experimental results, all energy levels in the conduction and in the valance band were calculated using transfer matrix technique, taking into account the effective mass and the parabolic band approximations. A comparison of the PR results with the calculated optical transition energies showed an excellent agreement. Several optical transition energies of the QWIP structures were resolved from PR measurements. It is concluded that PR spectroscopy is a very useful experimental tool to characterize complicated structures with a high accuracy at room temperature.

KeywordsPhotomodulated reflectance Quantum well infrared photodetectors QWIP Aspnes’ third derivative form Excitonic levels. 85.30.De 85.60.-q 71.55.Eq. AbbreviationsMQWmulti-quantum well

PLphotoluminescence

PRphotomodulated reflectance

QWquantum well

QWIPquantum well infrared photodetector

Rreflectance

TDFFthird derivative functional form.

Electronic supplementary materialThe online version of this article doi:10.1186-1556-276X-7-622 contains supplementary material, which is available to authorized users.

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Autor: Omer Donmez - Ferhat Nutku - Ayse Erol - Cetin M Arikan - Yuksel Ergun

Fuente: https://link.springer.com/







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