Japanese Journal of Applied Physics · 2003 · 42 citations · 2 references
EngineeringMaterials EngineeringMaterials ScienceCondensed Matter PhysicsOptoelectronicsSemiconductor MaterialsOptical Properties Of SemiconductorsQuantum WellsSemiconductor InterfacesSemiconductor PhysicsWide Band Gap SemiconductorsWide-bandgap SemiconductorsAbsorption SpectraElectric Field EffectsInfrared Absorption SpectraInfrared SpectraOptical Absorption SpectraOptical SwitchesQuantum Well HeterostructuresQuantum Well Structures
Intersubband transitions in GaN multiple quantum wells (MQW) are expected to be applicable to 1-Tb/s all-optical switches. The near-infrared (1.33–2.15 µm) intersubband absorption spectra of GaN/AlN MQW samples have been theoretically investigated. The measured spectra have been well explained by a model in which zero-voltage drop across one quantum well period and 0.5- to 0.75-nm-thick interface graded layers were assumed. The effective electric field in the well was estimated to be greater than 5 MV/cm. For thick wells, absorption spectra are sensitive to the electric field, and hence to the strain, barrier thickness, and doping level. In thin wells, the effect of the electric field is negligible, but the quality of the interface affects the spectra. The calculation model has been applied to the design of coupled quantum wells (CQW), where faster optical response is expected. Higher-order intersubband absorption at wavelengths of less than 1 µm is also expected to be enhanced in CQWs.
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