Pressure-Driven Reordering of Valence Band States in AlGaN/AlN Quantum Wells |
| S.P. Łepkowski a and W. Bardyszewski b
aInstitute of High Pressure Physics, "Unipress", Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warszawa, Poland bInstitute of Theoretical Physics, Faculty of Physics, University of Warsaw, Hoża 69, 00-681 Warszawa, Poland |
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| We study theoretically the influence of external hydrostatic pressure on the valence band structure in [0001]-oriented AlxGa1 - xN/AlN quantum wells used in deep-ultraviolet light emitting devices. The calculations performed using the multi-band k·p method with excitonic effects show that for AlxGa1 - xN/AlN quantum wells with x = 0.7 and quantum well width of 1.5 nm, reordering of the topmost valence subbands having different symmetries occurs with increasing pressure. In these structures, at low pressure values the topmost valence level is of Γp9 symmetry whereas it changes to the Γp7 state for pressures about 2.5 GPa. We also find that the excitonic effects increase the critical value of pressure at which the change in the polarization of the emitted light occurs to 7 GPa. This behavior is opposite to the pressure-dependent reordering of the topmost valence band states in thin GaN/AlGaN quantum wells which occurs from Γp7 to Γp9 states. |
| DOI: 10.12693/APhysPolA.122.1029 PACS numbers: 78.55.Cr, 78.67.De, 62.50.-p |