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Broadband Quantum Well Infrared Photodetector (qwip)

Posted on:2007-11-02Degree:DoctorType:Dissertation
Country:ChinaCandidate:J ZhangFull Text:PDF
GTID:1118360185984156Subject:Microelectronics and Solid State Electronics
Abstract/Summary:PDF Full Text Request
GaAs/AlxGa1-xAs quantum well infrared photodetectors (QWIP) are most attactive and progressed rapidly in recent 20 years due to its inherent properties, such as highly sensitive, wavelength tailorability, higher fabrication uniformity and better production yield. However, the responsivity spectrum of a typical QWIP is inherent narrower and sharper, so the quality of imaging becomes poor because of loss of light signal.. Thus, it is an important research subject to enlarge the spectral bandwidth. In order to overcome the main limitations of narrower spectral bandwidth, we discuss here our work on improving spectral bandwidth based on both theory analysis and experimental results. The main contents are followings:Based on the model of electron interference, the electron sublevels were calculated for the GaAs/AlxGa1-xAs Multi-quantum well (MQW ) structure. The calculated results indicate that there may be a series of separated conduction states and local states above the barriers. The electrons occupying the conduction states can transport along the direction perpendicular to the interfaces in a MQW structure, while those who occupy the local states cannot because they are basically confined in the quantum well layer. And the calculated results based on the theory of electron interference were compared with the theoretical results of K.P. model.Several photocurrent peaks were observed in the measured photocurrent spectrum for the GaAs/AlxGa1-xAs Multi-quantum well structure, and the calculated positions of the photocurrent peaks based on the model of electron interference are in good agreement with experimental ones.The conduction microband or the local microband is not single electron level, but energy band with definite energy range. When a strong electric field is applied along the growth axis of a multi-quantum well, Wannier-Stark ladder is formed based on the split of conduction microband. When photo excitations occur, electrons in a quantum well can not only vertically transit from the ground state to the conduction...
Keywords/Search Tags:Electron interference, Broadband, Multi-quantum well (MQW), Infrared photodetector
PDF Full Text Request
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