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24 April 1995 Monolithic integration of 1.3-μm InGaAs photodetectors and high-electron-mobility transistor (HEMT) electronic circuits on GaAs
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For the first time, monolithic optoelectronic receivers for a wavelength of 1.3 micrometers have been fabricated successfully on GaAs substrates using InGaAs metal-semiconductor-metal (MSM) photodiodes and AlGaAs/GaAs/AlGaAs high-electron-mobility transistors (HEMTs). Using molecular beam epitaxy (MBE), the photodetector layers were grown on top of a double (delta) -doped AlGaAs/GaAs/AlGaAs HEMT structure which allows the fabrication of enhancement and depletion field effect transistors. The photoabsorbing InGaAs layer was grown at 500 degree(s)C. To fabricate the optoelectronic receivers, first, an etch process using a combination of non-selective wet etching and selective reactive ion etching was applied to produce mesas for the photoconductors and to uncover the HEMT structure in all other areas. For the electronic circuits, our well-established HEMT process for 0.3-micrometers transistor gates was used which includes electron-beam lithography for gate definition and optical lithography for NiCr thin films resistors, capacitors, and inductors. The interdigitated MSM photodiode fingers were also fabricated using electron-beam lithography. For interconnecting the electronic circuits and the photodetectors, air bridges were employed. The entire process was performed on 2-inch wafers with more than 90% yield of functional receivers. The finished receiver--basically an MSM photodetector linked to a transimpedance amplifier--is operational at an incident wavelength of 1.3 micrometers at data rates up to 1.2 Gbit/s. The sensitivity of the detectors is 0.16 A/W at a 10 V bias.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Thomas Fink, Volker Hurm, Brian Raynor, Klaus Koehler, Willy Benz, and M. Ludwig "Monolithic integration of 1.3-μm InGaAs photodetectors and high-electron-mobility transistor (HEMT) electronic circuits on GaAs", Proc. SPIE 2397, Optoelectronic Integrated Circuit Materials, Physics, and Devices, (24 April 1995);

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