Very high photoconductive gain of about 104–105 is observed in GaAs photoconductive detectors for low photon flux density of 1015–1017 photons/(cm2·s). This high gain decreases with increasing photon flux density. A model is proposed which includes carrier separation by surface band dending and surface recombination of photogenerated carriers controlled by surface barrier height. This model is shown to quantitatively explain the photon flux density dependence of both high gain and response time.

In order to realize high speed, crosstalk-free interconnections with high noise immunity for very high speed IC's and systems, GaAs integrated photoconductive detector/FET receivers with a distributed coupling to optical fibers are developed. The distributed coupling enables a quick and simple connection between the integrated receiver and an optical fiber, with relatively low connection loss of -1.4 dB. The integrated receivers show response of 5 ns rise time for a 0.85 µm light pulse, which is limited by the surface effect of the detector.

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This paper presents the first successful application of a selective MOCVD growth to fabrication of a planar buried heterostructure laser diode. Double heterostructure of GaAs/AlGaAs laser was grown at atmospheric pressure, and the second-step selective growth for making a burying AlGaAs semi-insulating layer was carried out at low pressure. Resistivity of the undoped AlGaAs layer, controlled by changing V/III ratio, was more than 107 Ω·cm at V/III=100. The lasing wavelength was 879 nm and the threshold current of CW operation was 20 mA at room temperature.