The effect of the period number and barrier width on Superlattice Infrared Photodetector

Autor: Chih-Li Wang, 王智立
Rok vydání: 2004
Druh dokumentu: 學位論文 ; thesis
Popis: 92
The superlattice infrared photodetectors (SLIP) have drawn much attention since the observation of intersubband absorption in the far infrared region. It may be useful in many civilian, military, and scientific applications. In this thesis, we investigate the SLIP with the structure containing a current blocking layer embedded between two superlattice with different period numbers. We have designed two similar detectors to compare the performances. One of the detectors called D3 contains the 1000nm blocking barrier. The other called D6 contains the 300nm bolocking layer, while the superlattice structure of these two samples are the same except the doping density. This double-superlattice structure shows switchable spectral responses between two spectral regions by changing the voltage polarities. The photoresponse in each spectral region is also tunable by the magnitude of the applied voltage. By the simple fabrication process of samples into devices, and the measurement setup, we could measure the electrical and optical properties of our devices. Both of our detectors’ responsivity will be increased at long wavelength range as the temperature raise. This is due to the thermal excitation effect. We have compared the rsponsivity, dark current and photocurrent of these two samples and it is concluded that the responsivity from the sample with thin blocking barrier is affected by the group velocity at the second miniband and the responsivity of the thick barrier one is affected by the energy of the excited electron at second miniband. The thick blocking barrier will not only reduce the dark current but also the responsivity and photocurrent. Therefore, the detectivity for the thick barrier SLIP is at the same order for the thin one.
Databáze: Networked Digital Library of Theses & Dissertations
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