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Proceedings Paper

MOVPE of GaSb/InGaAsSb multilayers and fabrication of dual band photodetectors
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Paper Abstract

Metalorganic vapor phase epitaxy (MOVPE) of GaSb/InGaAsSb multilayer thin films and fabrication of bias-selectable dual band photodetectors are reported. For the dual band photodetectors the short wavelength detector, or the upper p-GaSb/n-GaSb junction photodiode, is placed optically ahead of the long wavelength one, or the lower photodiode. The latter is based on latticed-matched In0.13Ga0.87As0.11Sb0.89with bandgap near 0.6 eV. Specifically, high quality multilayer thin films are grown sequentially from top to bottom as p+-GaSb/p-GaSb/n-GaSb/n-InGaAsSb/p-InGaAsSb/p-GaSb on undoped p-type GaSb substrate, and as n-GaSb/p-GaSb/p-InGaAsSb/n-InGaAsSb/n-GaSb on Te-doped n-type GaSb substrate respectively. The multilayer thin films are characterized by optical microscope, atomic force microscope (AFM), electron microprobe analyses etc. The photodiode mesa steps are patterned by photolithography with wet chemical etching and the front metallization is carried out by e-beam evaporation with Pd/Ge/Au/Ti/Au to give ohmic contact on both n- and p-type Sb based layer surfaces. Dark I-V measurements show typical diode behavior for both the upper and lower photodiodes. The photoresponsivity measurements indicate that both the upper and lower photodiodes can sense the infrared illumination corresponding to their cutoff wavelengths respectively, comparable with the simulation results. More work is underway to bring the long wavelength band to the medium infrared wavelength region near 4 μm.

Paper Details

Date Published: 19 August 2005
PDF: 8 pages
Proc. SPIE 5881, Infrared and Photoelectronic Imagers and Detector Devices, 588101 (19 August 2005); doi: 10.1117/12.614208
Show Author Affiliations
Yegao Xiao, Rensselaer Polytechnic Institute (United States)
Ishwara Bhat, Rensselaer Polytechnic Institute (United States)
Tamer F. Refaat, Science and Technology Corp., NASA Langley Research Ctr. (United States)
M. Nurul Abedin, NASA Langley Research Ctr. (United States)
Qinghui Shao, Rensselaer Polytechnic Institute (United States)

Published in SPIE Proceedings Vol. 5881:
Infrared and Photoelectronic Imagers and Detector Devices
Randolph E. Longshore, Editor(s)

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