The effect of the selective doping and barrier width on Superlattice Infrared photodetector with the different period number
碩士 === 國立臺灣大學 === 電子工程學研究所 === 93 === The domain of superlattice investigation, we want to produce the larger wavelength range and higher photoresponse. Then, we change the structure to get the better responsivity. In this thesis, we investigated the two samples S1 and S2. Both samples contain a cur...
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| Format: | Others |
| Language: | en_US |
| Published: |
2005
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| Online Access: | http://ndltd.ncl.edu.tw/handle/72222758472964195280 |
| Summary: | 碩士 === 國立臺灣大學 === 電子工程學研究所 === 93 === The domain of superlattice investigation, we want to produce the larger wavelength range and higher photoresponse. Then, we change the structure to get the better responsivity.
In this thesis, we investigated the two samples S1 and S2. Both samples contain a current blocking layer embedded between two superlattice with different period numbers. One of the detectors called S1 contains 50nm blocking barrier and doped in every well in superlattice. The other called S2 contains 300nm blocking barrier and only doped in the middle period of each three periods in superlattice. We can switch the spectral response between two superlattice by changing the voltage polarities.
The first discussion is about the effect of period number. We observed the responsivity of 3-period superlattice is larger than 15-period one in the low bias. This is due to the electron group velocity of 3-period in the second miniband is larger than 15-period. Then, we discuss the effect of the different doped method and the different blocking barrier thickness. We find that the doped method will change the photoresponse shape. The selective doped method has different peak with the uniformly doped layers. Because the different doping density has different Fermi level to affect our design energy band states. We have compared the current curve. 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.
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