Optical waveguide detection: Photodetector array formed on the waveguide utilizing laser recrystallized silicon

Abstract

Integrated detection of light propagating in an optical waveguide with a photodetector array fabricated directly on the waveguide surface is demonstrated. Laser recrystallization of polycrystalline silicon is utilized. Periodically spaced antireflection stripes are used to confine grain boundaries formed during laser recrystallization to the area under these stripes, with photodetector elements formed on single crystal grains between the stripes. Regions containing the grain boundaries are then removed by plasma etching. Lateral p-i-n photodiode elements formed by ion implantation are characterized by reverse leakage currents <10−11 A and breakdown voltages of 40–80 V. Dynamic ranges over which the optical response is linear are measured to be 55–60 dB.