Photodetectors fabricated on heteroepitaxial GaAs/Si structures grown by molecular beam epitaxy

✍ Scribed by N.A. Papanicolaou; G.W. Anderson; J.A. Modolo; A. Georgakilas

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 562 KB
• Volume: 8
• Category: Article
• ISSN: 0749-6036
• DOI: 10.1016/0749-6036(90)90246-4

✦ Synopsis

Photodetectors were fabricated on GaAs/Si epitaxial structures grown on high resistivity Si substrates by modulated molecular beam epitaxy. Our efforts were focused on enhancing the substrate surface quality and optimizing the deposition conditions during the early stages of growth of the GaAs on the Si substrates. The photodetector structures investigated consisted of a 30oA thick GaAs/AlAs nucleation layer, a 5-period GaAs (l~A)/AlAs(1OOA) accommodation layer grown at 300°C, two GaAsJInGaAs strained layer superlatices separated by a GaAs spacer layer, and a 2trm undoped GaAs active photodetector layer, a 0.2um n-GaAs and a n+-GaAs contact layer. Various photodetector configurations fabricated in these GaAs/Si material structures were investigated.

The photodetector response measurements were made using a 840nm wavelength pulsed laser with a pulse width of 5ns and rise (tr) and fall (tt) times of 2OOps. Typical rise and fall times of the photodetectors were in the l-2 ns and 3-6 ns ranges, respectively.

The responsivity and quantum efficiency values of these photodetectors were in the ranges of 0.5-1 .O A/W and 0.3-1.5, respectively.