HIGH-SPEED METAL-SEMICONDUCTOR-METAL PHOTODIODES WITH ER-DOPED GAAS

Abstract

Very high-speed MSM photodiodes have been fabricated on Er-doped GaAs over a doping range of 10(18)-10(20) cm-3. The impulse response (characterized by photoconductive sampling) of these diodes, with finger widths/spacings of 2 mum, has been found to be tunable over a range of about 3 ps-22 ps. Electro-optic sampling was used to characterize MSM diodes with finger widths/spacings of 0.5 mum and 1 mum on a sample with [Er] = 10(19) cm-3, resulting in 3-dB bandwidths of 160 GHz and 140 GHz, respectively, corresponding to pulse widths of 2.7 ps and 3.3 ps. Correlation measurements were also done on the GaAs:Er samples, using an all-electronic Sampling Optical Temporal Analyzer (SOTA) structure.