Wojciech P. Giziewicz

High performance, waveguide integrated Ge photodetectors

Photonic systems based on complementary metal oxide semiconductor (CMOS) technology require the integration of passive and active photonic devices. The integration of waveguides and photodetector is one of the most important technologies. We report a Ge p-i-n photodetector that is monolithically integrated with silicon oxynitride and silicon nitride waveguides. All processes and materials are CMOS compatible and can be implemented in the current integrated circuit process technology. The small size of the devices results in low absolute dark current. The waveguidecoupled Ge devices show high efficiency (~90%) over a wide range of wavelengths well beyond the direct band gap of Ge, resulting in a responsivity of 1.08 A/W for 1550 nm light. The device speed of 7.2 GHz at 1V reverse bias is strongly affected by the capacitance of the probe pads. The high-performance of the devices at low voltage ( </= 1V) facilitates the integration with CMOS circuits.

High-performance, tensile-strained Ge p-i-n photodetectors on a Si platform

We demonstrate a high-performance, tensile-strained Ge p-i-n photodetector on Si platform with an extended detection spectrum of 650–1605 nm and a 3 dB bandwidth of 8.5 GHz measured at λ=1040nm. The full bandwidth of the photodetector is achieved at a low reverse bias of 1 V, compatible with the low driving voltage requirements of Si ultralarge-scale integrated circuits. Due to the direct bandgap shrinkage induced by a 0.20% tensile strain in the Ge layer, the device covers the entire C band and a large part of the L band in telecommunications. The responsivities of the device at 850, 980, 1310, 1550, and 1605 nm are 0.55, 0.68, 0.87, 0.56, and 0.11A∕W, respectively, without antireflection coating. The internal quantum efficiency in the wavelength range of 650–1340 nm is over 90%. The entire device was fabricated using materials and processing that can be implemented in a standard Si complementary metal oxide semiconductor (CMOS) process flow. With high speed, a broad detection spectrum and compatibility ...

Advances in fully CMOS integrated photonic devices

The complete integration of photonic devices into a CMOS process flow will enable low cost photonic functionality within electronic circuits. BAE Systems, Lucent Technologies, Massachusetts Institute of Technology, Cornell University, and Applied Wave Research are participating in a high payoff research and development program for the Microsystems Technology Office (MTO) of DARPA. The goal of the program is the development of technologies and design tools necessary to fabricate an application specific, electronic-photonic integrated circuit (AS-EPIC). The first phase of the program was dedicated to photonics device designs, CMOS process flow integration, and basic electronic functionality. We will present the latest results on the performance of waveguide integrated detectors, and tunable optical filters.

High performance Ge p-i-n photodetectors on Si

We demonstrate a high performance Ge p-i-n photodetector on Si platform with an extended detection spectrum of 650-1605 nm, a 3 dB bandwidth of 8.5 GHz, and a responsivity of 0.68 A/W, measured at /spl lambda/ = 1040 nm.

Lateral p-i-n photodetectors fabricated in a standard commercial GaAs VLSI process

Lateral detectors fabricated in an unmodified commercial GaAs VLSI process are presented. The detectors exhibit previously observed characteristic sensitivity and capacitance properties. High speed measurements indicate a bandwidth in excess of 4 GHz.

Measurement and modeling of high-performance lateral p-i-n photodetectors

Laterial p-i-n photodiodes have been produced in a standard, unmodified commercial GaAs integrated circuit process (Vitesse Semiconductor Inc. HGaAs IV and V). The devices were modelled using the MEDICI simulation package, achieving a very good fit to both capacitance and DC light response measuremnts. The simulation recreated an interesting feature of the devices, wherein the detectors go from a low-performance to high-performance regime abruptly at a specific reverse bias. An analysis of the simulated behavior of the depletion region in the nominally intrinsic region of the device provided a partial answer to the physics behind this bias point. A second generation of devices of different geometries was fabricated and tested. The newer fabrication process showed a lower performance transition (~0.6 V) than the previous process (~4 V) for an identical layout geometry. Preliminary high-speed measurements of the newer devices are quite encouraging.

Optoelectronic integration using aligned metal-to-semiconductor bonding

A method to monolithically integrate optoelectronic devices with separately fabricated very large scale integrated circuitry has been investigated, and an aligned bonding procedure involving an intermediary metal film has been developed. The optoelectronic device heterostructures are grown epitaxially and patterned on the growth substrate, and then aligned to and bonded into dielectric wells on the target integrated circuit (IC) substrate, an entire wafer at a time. The metal film structure is responsible for the mechanical attachment of the devices to the integrated circuit substrate as well as for the ohmic contact between the parts. Bonding is performed at a low enough temperature to prevent damage to the electronics on the target substrate. Finally, the growth substrate is removed and the heterostructures are processed into optoelectronic devices integrated monolithically with the electronics, leaving a relatively planar optoelectronic integrated circuit. Results will be presented from initial experim...

A 20 GHz, tensile strained Ge photodetector on Si platform with detection spectrum for optical communications and on-chip applications

This paper presents a 20 GHz Ge photodetector on Si platform that covers a broad detection spectrum from 850-1600 nm. This device has promising applications in high capacity optical communications and on-chip Si optoelectronic circuits.

High Speed Ge Photodetectors on Si Platform for GHz Optical Communications in C+L Bands

We present a high speed, high responsivity, tensile strained Ge p-i-n photodetector selectively grown on Si platform that covers the whole C band and a large part of the L band for high capacity optical communications. The device shows a 3dB bandwidth of 2.5GHz and its responsivities at 1310nm and 1550nm are comparable to commercial InGaAs photodetectors currently used in telecommunications. The device has promising applications in Si microphotonics such as the fiber-to-the-home technology.

Large Diameter, CMOS-Manufacturable Photodetectors for over 2 Gbps Polymer Optical Fiber Applications

Lateral p-i-n photodetectors were fabricated in a CMOS-compatible process. The 200µm diameter devices had a bandwidth of 1.7 GHz, suitable for 2.5 Gbps operation. An unexpected illumination intensity dependance was observed and confirmed by simulation.