This thesis reports a detailed characterization of indium arsenide antimonide (InAs1-
xSbx) photodetectors grown on gallium arsenide (GaAs) substrate by molecular
beam epitaxy. A combination of polyimide and sulphur and a single layer of
polyimide were used as passivation films in this study. Two different epilayer
structures were used for assessing the detector performance and comparing the
above passivation layers. For the first structure, the optical measurements revealed
that Sb mole fraction was 0.13 and the cut-off wavelength was around 4.1 µ / m at 80
K. The Sb mole fraction of the second structure was 0.2, and the 77 K cut-off
wavelength was 4.8 µ / m. Detailed electrical and optical characterizations were
performed on 33x33 µ / m2 test diodes. The photodiodes yielded peak detectivities of
~3.65x1010 and ~1.22x1010 cmHz1/2/W at 80 K for the first and second structures,
respectively. Considerable 1/f noise current related with trap-assisted tunneling mechanism was observed in both structures at 80 K.
Dark current modeling study showed that the dark current was dominated by the
shunt and trap-assisted tunneling mechanisms throughout the entire reverse bias
voltages for both detectors. The dark current analysis of variable area detectors
fabricated with both epilayer structures revealed that the reverse bias current was
mainly generated by the surface leakage in small sized (33x33 µ / m2) detectors for
both passivation layers. However, the surface current contribution was observed to
be lower for the double layer (polyimide and sulphur) passivated detectors
suggesting that it is a better passivation technique.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/2/12606875/index.pdf |
| Date | 01 December 2005 |
| Creators | Ersagun, Ozlem |
| Contributors | Besikci, Cengiz |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for METU campus |
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