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In this article, the realization and characterization of a new kind of resonant cavity enhanced photo-detector, fully compatible with silicon microelectronic technologies and working at 1.55 μm, are reported. The detector is a resonant cavity enhanced structure incorporating a Schottky diode, and its working principle is based on the internal photo-emission effect. A comparison between a Schottky diode (Al/Si or Cu/Si) and the Schottky diode fed on a high-reflectivity Bragg mirror is carried out. Considering Al as Schottky metal, no difference in responsivity is obtained; considering Cu as Schottky metal, a three-fold responsivity improvement is experimentally demonstrated.

The realization of on-chip optical interconnects requires the integration of active micro-optical devices with microelectronics. However, it is not clear yet how silicon photonics could be integrated within CMOS chips. In this context the non-crystalline forms of silicon, such as laser-annealed polycrystalline and hydrogenated amorphous silicon (a-Si:H), can deserve some advantages as they can be included almost harmlessly everywhere in a CMOS typical run-sheet, yielding low-cost and flexible fabrication. In particular, a-Si:H can be deposited using the CMOS-compatible low temperature plasma enhanced chemical vapour deposition (PECVD) technique, which brings clear advantages particularly for a back-end photonic integrated circuit (PIC) integration. However, till now a-Si:H has been mainly considered for the objective of passive optical elements within a photonic layer at λ=1.55 μm. Only a small number of examples have been reported, in fact, on waveguide integrated active devices. In this paper we detail about an effective refractive index variation obtained through an electrically induced carrier depletion in an as-deposited a-Si:H-based p-i-n waveguiding device. For this device switch-on and switch-off times of ~2 ns were measured allowing a modulation rate higher than 150 MHz.yy

A very simple and fast MachZehnder electro-optic modulator based on a p-i-n configuration, operating at lambda = 1.55 mu m, has been fabricated at 170 degrees C using the low cost technology of hydrogenated amorphous silicon (a-Si:H). In spite of the device simplicity, refractive index modulation was achieved through the free carrier dispersion effect resulting in characteristic rise and fall times of similar to 2.5 ns. By reverse biasing the p-i-n device, the voltage-length product was estimated to be V-pi center dot L-pi = 40 V center dot cm both from static and dynamic measurements. Such bandwidth performance in as-deposited a-Si:H demonstrates the potential of this material for the fabrication of fast active photonic devices integrated on standard microelectronic substrates.

A p-i-p configuration of an electro-optical modulator based on hydrogenated amorphous silicon (a-Si:H) is characterized and compared with an a-Si:H based p-i-n modulator. In particular, we estimate the performances in terms of optical losses, voltage-length product, and bandwidth at ? ¼ 1550 nm for waveguide-integrated p-i-p versus p-i-n configurations. Both devices are fabricated on a silicon substrate by plasma enhanced chemical vapor deposition at low temperature ensuring the back-end integration with a CMOS microchip. We demonstrate a factor of merit for the p-i-p waveguide integrated Fabry-Perot resonator of V? ×L? ¼ 19 V × cm allowing the design of shorter devices with respect to p-i-n structure.