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Article Dans Une Revue Physical Review B Année : 2020

Hydrostatic pressure dependence of indirect and direct excitons in InGaN/GaN quantum wells

Résumé

We analyze the evolution of the exciton recombination energy (EPL) and its pressure coefficient (dEPL/dp) with the laser power density (LPD) exciting excitonic photoluminescence. Two In0.17Ga0.83N/GaN quantum well (QW) structures are used: sample A consisting of a 5.2-nm-wide single QW and sample B consisting of two 2.6-nm-wide QWs separated by a 0.78-nm-thick barrier. Changes of EPL and dEPL/dp with LPD in both structures cover a wide range of magnitude. They switch character in the vicinity of the indirect to direct exciton induced by increasing LPD. In sample B, at low excitation, a negative pressure coefficient of EPL has been found. Moreover, pressure dependences of EPL are different for the two samples under study. We examined pressure dependence of the threshold LPD for indirect-direct exciton switching in both samples. The reported observations originate to a high extent from screening of a built-in electric field by carriers externally introduced into the quantum wells. We also note that the universal relation between transition energies and their pressure coefficients (observed previously in InGaN/GaN quantum wells) does not hold for samples modified by screening.
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Dates et versions

hal-03116810 , version 1 (20-01-2021)

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G. Staszczak, W. Trzeciakowski, Eva Monroy, A. Bercha, G. Muzioł, et al.. Hydrostatic pressure dependence of indirect and direct excitons in InGaN/GaN quantum wells. Physical Review B, 2020, 101 (8), pp.314-319. ⟨10.1103/PhysRevB.101.085306⟩. ⟨hal-03116810⟩
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