AVS 52nd International Symposium
    Electronic Materials and Processing Thursday Sessions
       Session EM2-ThA

Paper EM2-ThA4
Electronic Properties of GaAsN Quantum Wells

Thursday, November 3, 2005, 3:00 pm, Room 310

Session: Dilute Nitrides and Small Bandgap Semiconductors
Presenter: S. Turcotte, École Polytechnique de Montréal, Canada
Authors: S. Turcotte, École Polytechnique de Montréal, Canada
N. Shtinkov, École Polytechnique de Montréal, Canada
J.-N. Beaudry, École Polytechnique de Montréal, Canada
G. Bentoumi, Université de Montréal, Canada
R.A. Masut, École Polytechnique de Montréal, Canada
R. Leonelli, Université de Montréal, Canada
P. Desjardins, École Polytechnique de Montréal, Canada
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Dilute semiconductor nitrides heterostructures are very promising for a variety of device applications including lasers and photovoltaic cells. The optimization of such devices relies on the understanding of the fundamental electronic properties of quantum well structures. Among these, optical transitions, quantum confinement, and band offsets need to be clarified. Using a combination of techniques including optical absorption and photoluminescence, we have studied GaAs@sub 1-x@N@sub x@ quantum wells in GaAs(001). Two series of samples grown by MOCVD were investigated. The first consists of 7-period, 10-nm-thick GaAs@sub 1-x@N@sub x@ multiple quantum wells (MQW) with x ranging from 0.001 to 0.02 as determined from high-resolution x-ray diffraction. A series of single quantum wells (SQW) was also fabricated to investigate the effect of well thickness, from 2.8 to 11.3 nm, for a nominal N content of x=0.01. The low-temperature (near 5K) PL spectra of the MQWs are characterized by a 10-20 meV wide emission peak at an energy decreasing from 1.5 eV to 1.3 eV with increasing N content. Annealing at 700°C for 2 min. resulted in more intense PL emission with negligible change in energy. Electronic structure calculations are carried out using a tight-binding model.@footnote 1,2@ We obtain an excellent agreement between experimental and numerical results for the case corresponding to perfectly aligned GaAs and GaAsN valence bands. The absorption edge measured at 6 K for the SQWs structures decreases from 1.45 to 1.35 eV with increasing thickness. By fitting these results to the tight-binding calculations, we deduce an electronic confinement of the order of 55 meV and 125 meV for the thickest and thinnest layers, respectively. @FootnoteText@ @footnote 1@ N. Shtinkov, P. Desjardins, and R. A. Masut, Phys. Rev. B 67, 081202(R) (2003)@footnote 2@ N. Shtinkov, S. Turcotte, J.-N. Beaudry, P. Desjardins, and R. A. Masut, J. Vac. Sci. Technol. A 22, 1606 (2004)