Switching of exciton character in double InGaN/GaN quantum wells.

T. Suski (1) , G Staszczak (1) , K Korona (2) , Pierre Lefebvre (3) , E. Monroy (4) , P Drozdz (1) , Grzegorz Muziol (1) , C. Skierbiszewski (1) , K Gibasiewicz (1) , P Perlin (1)

1 IHPP - Institute of High Pressure Physics [Warsaw]
2 IFD - Institute of Experimental Physics [Warsaw]
3 L2C - Laboratoire Charles Coulomb
4 NPSC - Nanophysique et Semiconducteurs

We study the inter-well excitonic coupling in a series of In0.17Ga0.83N/GaN Double QWs (DQWs) with varying central barrier width. We observe the switching between indirect IX (inter-well) and direct DX (intra-well) excitons, for thin barriers (2 nm or less), depending on the exciton density. This density is controlled, in cw-PL, by the pumping laser power density (LPD). Above a certain threshold, we observe a sudden change of the PL blue-shift, when switching from IXs (large slope) to DXs (weak slope). In time-resolved PL, the exciton density evolves as the PL intensity decays with time, and the switching occurs from DXs to IXs, after a certain characteristic time. The decay time of IXs is of the order of hundreds of s, whereas the decay time of DXs is shorter by three orders of magnitude. The switching thresholds in both cw- and TR-PL present clear exponential dependences upon the width of the central barrier, which demonstrates the role of carrier tunneling in the overall switching processes. The described effects were studied at T10K but we found that IXs persist up to T=300K pointing out the importance of large exciton biding energy in nitride QWs.

Domaines: Science des matériaux [cond-mat.mtrl-sci]; Micro et nanotechnologies/Microélectronique; Optique / photonique

T. Suski, G Staszczak, K Korona, Pierre Lefebvre, E. Monroy, et al.. Switching of exciton character in double InGaN/GaN quantum wells.. International Workshop on Nitride semiconductors - IWN2018., Nov 2018, Kanazawa, Japan. ⟨hal-01908886⟩