Quantum Structure Long-wavelength Light Emitting Devices Using Heterojunction Energy Filters

点击翻译按钮获取中文摘要

Research on the basic properties of the inter-subband optical transition in compound semiconductor quantum structures was carried out to gain the understanding required to realize long-wavelength light emitting devices utilizing the inter-subband optical transitions.The following two quantum structures were investigated theoretically and both are shown to be able to be used to realize long-wavelength LED's : (1) InAs/AlSb/GaSb quantum structures in which all the electrons pass through the structure undergo inter-subband transition, and (2) energy filter structures utilizing more mature AlGaAs/GaAs systems. Population inversion was also shown to be realized by the two structures even under the fast nonradiative relaxation by optical phonons.On the experimental side, AlGaAs/GaAs structures were grown and the inter-subband absorption under electric fields was measured to clarify the effect of electric field on the transition. It was found that the absorption energy shifted toward low energy when carrier concentration in the well was high, whereas it shifted toward high energy when carrier concentration was low (Stark shift).Experiments are under way to experimentally realize the LED's based on the inter-subband transitions in these structures.