8-element linear array monolithic p-i-n MODFET photoreceivers using molecular beam epitaxial regrowth

An 8-element linear array of single-stage integrating front-end photoreceivers using molecular beam epitaxial (MBE) regrowth was investigated. Each element consisted of a p-i-n In/sub 0.53/Ga/sub 0.47/As photodiode integrated with a selectively regrown pseudomorphic In/sub 0.65/Ga/sub 0.35/As/In/sub 0.52/Al/sub 0.48/As MODFET. Cutoff frequencies of 1.0- mu m discrete regrown MODFETs were f/sub t/=24 GHz and f/sub max/=50 GHz. Transconductance of the regrown MODFETs was as high as 495 mS/mm with a current density (I/sub ds/) of 250 mA/mm. The 3-dB bandwidth of the photoreceiver was measured to be 1 GHz. The bit rate sensitivity at 1 Gb/s was -31.8 dBm for BER 10/sup -9/ using 1.55 mu m excitation for a photoreceiver with an anti-reflection coating. The single-stage amplifier exhibited up to 25 dB flatband gain of the photocurrent, and a two-stage amplifier was up to 31 dB of gain. Good uniformity between each photoreceiver element in the array was achieved. Electrical crosstalk between photoreceiver elements was estimated to be approximately -34 dB.<
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