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Surprisingly low built-in electric fields in quaternary InAlGaN heterostructures
|S. Anceau 1,2, Pierre LEFEBVRE 2, L. Kończewicz 2, Tadeusz Suski 1, S. P. Lepkowski 1, H. Teisseyre 1, Agata Kamińska 3, Andrzej Suchocki 3, H. Hirayama 4, Y. Aoyagi 4|
1. Polish Academy of Sciences, High Pressure Research Center (UNIPRESS), Sokolowska 29/37, Warszawa 01-142, Poland
In ternary InGaN/GaN or GaN/AlGaN quantum wells (QWs) grown along the (0001) direction, presence of large internal strain results in a piezoelectric polarization and thus in a built-in electric field in the QW layers. Moreover, spontaneous polarization characteristic for nitrides crystallizing in wurtzite structures causes an increase of the built-in electric field in both InGaN/GaN and GaN/AlGaN QWs. The large internal electric fields induce in turn the separation of the electron and hole wavefunctions in the QW and a reduction of the optical transition matrix element. This effect is known as the Quantum Confined Stark Effect (QCSE). On the contrary, for the case of quaternary InAlGaN based QWs one may consider cases where the QWs are strained (with compressive or tensile strain) or unstrained. Particularly, one may expect that, for properly chosen compositions of barriers and QWs, the internal electric field is negligible since a term coming from the spontaneous polarization cancels a term from the piezoelectric effect. In such a case no reduction of the optical transition probability due to QCSE occurs.
Presentation: oral at E-MRS Fall Meeting 2003, Symposium A, by S. Anceau
See On-line Journal of E-MRS Fall Meeting 2003
Submitted: 2003-05-27 10:37 Revised: 2009-06-08 12:55