0000000000240832
AUTHOR
Jean Massies
Microcavity Light Emitting Diodes Based on GaN membranes Grown by Molecular Beam Epitaxy on Silicon
Resonant-cavity InGaN/GaN quantum well light emitting diodes have been fabricated. Nitride layers were grown by molecular beam epitaxy on Si (111). We fabricated the structures using a combination of Si substrate etching, GaN etching and dielectric (Ta2O5/SiO2) mirror deposition. The electroluminescence spectra show that the emission within the distributed Bragg reflector stop band is enhanced in the membrane microcavity. The cavity modes are broadened by some cavity length non-uniformity that is introduced when the GaN is back etched to adjust the cavity length. This process does not need any transfer on an intermediate host substrate and is fully compatible with large area semiconductor p…
Type II narrow double barrier quantum well structures : Γ-X coupling and interface effects
Photoluminescence (PL), PL excitation and time resolved PL experiments have been performed on Al0.42Ga0.58As/AlAs/GaAs symmetric double barrier quantum wells (DBQW) with only one or two AlAs monolayers constituting the intermediate barriers. In agreement with the envelope function predictions we show that such DBQW's undergo a type I - type II transition when the GaAs thickness is reduced below 7 and 5 monolayers for 2 and 1 AlAs molecular planes respectively. In type II configuration the PL decay time is found to be strongly dependent on the energy difference between AlAs Xz - and GaAs Γ - electron confined states and the coupling parameter of the Γ and Xz valleys can be deduced (4.2 meV o…
Controlled type-I–type-II transition in GaAs/AlAs/AlxGa1−xAs double-barrier quantum wells
We show that the insertion of extremely narrow AlAs layers in double-barrier GaAs/AlAs/${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As quantum wells results in a variety of electronic configurations, thus providing a powerful tool for tailoring the electronic transitions in GaAs heterostructures. In particular, the transition from type-I to type-II recombination is shown to occur in correspondence with variations by a single monolayer in the thickness of the AlAs and/or GaAs layers. Drastic changes in the recombination lifetimes are correspondingly observed; at the same time, the photoluminescence efficiency is found to be almost independent of the type-I-…