MSM Photodiode Research Articles

20 Gbit/s long wavelength monolithic integratedphotoreceiver grown on GaAs

The first 20 Gbit/s 1.3-1.55 /spl mu/m wavelength monolithic integrated photoreceiver grown on GaAs substrate has been fabricated using AlGaAs/GaAs HEMTs. At a wavelength of 1.3 /spl mu/m, the integrated InGaAs MSM photodiode has a responsivity of 0.32A/W and the photoreceiver has a -3 dB bandwidth of 16.5 GHz. Clearly-opened eye diagrams for a 20 Gbit/s 1.55 /spl mu/m optical data stream have been demonstrated.

Vertical MSM photodiodes in silicon based on epitaxial Si/CoSi 2/Si

We present performance data of new ultrafast metal–semiconductor–metal photodiodes, fabricated by Si/CoSi 2 layer growth on (100) and (111) silicon. The design of these vertical diodes avoids expensive direct electron beam writing. If a mode-locked Ti:sapphire laser of 800 nm wavelength and 0.15 ps pulse length is used for excitation from the top, the diodes deliver a fast electrical pulse response of 7 ps FWHM at 50 K for Si(100) and of 6.5 ps for Si(111), also at room temperature, which is in full agreement with the design parameters. Quantum efficiencies up to 15% seem to be feasible with an integrated optical waveguide which couples the light from the side into the photodiode.

20 Gbit/s fully integrated MSM-photodiode AlGaAs/GaAs-HEMToptoelectronic receiver

A 0.85 µm wavelength monolithic integrated optoelectronic receiver consisting of a GaAs MSM photodiode and a multi-stage AlGaAs/GaAs HEMT amplifier has been fabricated. The transimpedance is 12.6 kΩ (into 50 Ω) and the sensitivity is better than –14.7 dBm (at 12.5 Gbit/s, BER = 10-9). The bandwidth of 13.0 GHz implies suitability for transmission rates up to 20 Gbit/s.

10 Gbit/s long-wavelength monolithic integratedoptoelectronic receiver grown on GaAs

The first 10 Gbit/s long-wavelength monolithic integrated photoreceiver grown on GaAs substrate has been fabricated using a 0.3 µm gate length AlGaAs/GaAs HEMT process. At a wavelength of 1.3 µm the integrated InGaAs MSM photodiode has a DC responsivity of 0.34 A/W. The photoreceiver bandwidth is 7.1 GHz and its sensitivity is better than –14.7 dBm (BER = 10-9).

Low-frequency gain in MSM photodiodes due to charge accumulation and image force lowering

To understand the nature of low-frequency gain in MSM photodiodes, Schottky barrier height was measured for an MSM photodiode fabricated on GaAs-based layers. The Schottky barrier height showed a dependence on the light irradiation and bias. This can be explained by a lowering of the Schottky barrier due to charge accumulation at surface states and image-force lowering at the edges of metal electrodes where electric field is extremely high. Thermionic hole emission is proposed as a source of low-frequency gain of MSM photodiodes.

High optical power nonlinear dynamic response of AlInAs/GaInAs MSM photodiode

In this paper, we introduce a theoretical study and a numerical simulation of the nonlinear electrical response, including the harmonic-generation rate calculation, of an MSM AlInAs/GaInAs photodiode under high-illumination conditions. We also report that, with an MSM operating at 20 GHz, we can expect a saturation limit at a maximum modulated optical power as high as 100 mW. >

High-speed metal-semiconductor-metal photodiodes with Er-doped GaAs

Very high-speed MSM photodiodes have been fabricated on Er-doped GaAs over a doping range of 10/sup 18/-10/sup 20/ cm/sup -3/. The impulse response (characterized by photoconductive sampling) of these diodes, with finger widths/spacings of 2 /spl mu/m, 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 /spl mu/m and 1 /spl mu/m on a sample with [Er]=10/sup 19/ cm/sup -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. >

1.3 µm monolithic integrated optoelectronicreceiver using anInGaAs MSM photodiode and AlGaAs/GaAs HEMTs grown on GaAs

The first 1.3 µm monolithic integrated optoelectronic receiver using an InGaAs MSM photodiode and AlGaAs/GaAs HEMTs grown on a GaAs substrate has been fabricated. At each differential output of the implemented multistage amplifier the transimpedance is 26.8 kΩ (into 50 Ω). The bandwidth of 430 MHz implies suitability for transmission rates up to 622 Mbit/s.

Design and performance analysis of InP-based high-speed and high-sensitivity optoelectronic integrated receivers

A novel transimpedance optoelectronic receiver amplifier suitable for monolithic integration is proposed and analyzed by exploiting state-of-the-art high-speed MSM photodiodes and HBT's based on lattice-matched InGaAs-InAlAs heterostructures on InP substrates. The projected performance characteristics of this amplifier indicate a high transimpedance (/spl ap/3.6 k/spl Omega/), a large bandwidth (17 GHz), and an excellent optical detection sensitivity (/spl minus/26.8 dBm) at 17 Gb/s for the standard bit-error-rate of 10/sup /spl minus/9/. The latter corresponds to an input noise spectral density, /spl radic/(i/sub in//sup 2//B), of 2.29 pA//spl radic/(Hz) for the full bandwidth. The bandwidth of the amplifier can be increased to 30 GHz for a reduced transimpedance (0.82 k/spl Omega/) and a lower detection sensitivity, i.e., /spl minus/21 dBm at 30 Gb/s. The amplifier also achieves a detected optical-to-electrical power gain of 21.5 dBm into a 50 /spl Omega/ load termination. The design utilizes small emitter-area HBT's for the input cascoded-pair stage, followed by a two-step emitter-follower involving one small and one large emitter-area HBT's. The design strategy of using small emitter-area HBT's is matched by a low-capacitance novel series/parallel connected MSM photodiode. This combined approach has yielded this amplifier's combined high performance characteristics which exceed either achieved or projected performances of any receiver amplifier reported to-date. The paper also discusses the issues concerning IC implementation of the receiver, including the means of realizing a high-value feedback resistor. >

GaAs MSM Photodiode Using the Highly Doped Channel Layer of a Heterostructure MESFET

GaAs MSM Photodiode Using the Highly Doped Channel Layer of a Heterostructure MESFET

14 GHz bandwidth MSM photodiode AlGaAs/GaAs HEMT monolithic integrated optoelectronic receiver

A monolithic optoelectronic receiver consisting of an MSM photodiode and a two-stage amplifier has been fabricated using an enhancement/depletion 0.3 μm recessed-gate AIGaAs/GaAs HEMT process. The bandwidth of 14.3 GHz implies suitability for transmission rates of up to 20 Gbit/s. The transimpedance is 670 Ω (into 50 Ω) and the projected sensitivity is −16.4 dBm (BER = 10−9).

Integration of a Quantum Well Laser with AlGaAs/GaAs-HEMT Electronics

ABSTRACTIn this presentation the various technology steps for the monolithic integration of GaAs quantum well lasers with Double Pulse Doped AlGaAs/GaAs/AlGaAs Quantum Well (DPDQW) E/D HEMT electronics on a single substrate in one process run are described. All layers are grown by molecular beam epitaxy. The laser structure, consisting of three 74 Å GaAs quantum wells between two AlGaAs cladding layers, are grown on top of the electronic structure. The laser mesas and contact areas are defined by a combined wet and dry etch process. Apart from the transistor gates which are exposed by electron beam lithography, all lithography steps are performed using contact printing. A two layer metallization is used to interconnect the devices whereby air-bridges are used to connect the laser mesas to the electronics. First results showed laser action of laser diodes of area 3 x 300 μm2 at a threshold current of less than 60 mA, as well as the operation of different electronic devices on wafers which have been processed in this way. These include a laser diode driver, and an optoelectronic receiver with a MSM photo diode, both devices operating at a data rate of 5 Gbit/sec. These results indicate that the process sequence described is suitable for the integration of laser diodes and HEMT electronics.

X-ray detectors based on semi-insulating GaAs substrate

Abstract Semi-insulating GaAs is suitable as detector for X-rays and particles. Compared to silicon, charge carriers in GaAs have less effective mass, so they gain a higher acceleration. The detectors operate as Schottky diodes. Design and processing were carried out at the IAF in Freiburg. The layout contains quadratic diodes of various sizes (2×2 mm2, 3×3 mm2, etc.) and also microstrip detectors. Test measurements were made with α-, β- and γ-rays. For the first time X-rays down to 20 keV have been observed with room temperature GaAs. With γ-radiation of 57Co, 122 keV, an energy resolution of 18% FWHM was obtained. It is planned to integrate signal processing fast electronics on the same wafer. Also discussed is a data transfer by optoelectronical means, as for example laser diodes and MSM photodiodes.

Speed and sensitivity limitations of optoelectronic receivers based on MSM photodiode and millimeter-wave HBTs on InP substrate

Heterostructure bipolar transistors and MSM photodetectors based on compound semiconductors have demonstrated high-frequency performance beyond 100 GHz. By combining these state-of-the-art devices in a realistic integrated optoelectronic receiver, this letter demonstrates that it is possible to achieve a receiver sensitivity of -19.04 dBm at 16 Gb/s at a bit-error-rate of 10/sup -9/. Further improvement of noise and bit-rate can be achieved by designing HBTs with lower junction capacitances. >

8.2 GHz bandwidth monolithic integrated optoelectronic receiver using MSM photodiode and 0.5 μm recessed-gate AlGaAs/GaAs HEMTs

An 8.2 GHz bandwidth monolithic optoelectronic receiver consisting of an MSM photodiode, a transinipedance amplifier, and a 50Ω output buffer has been fabricated using an enhancement/depletion 0.5/an recessed-gate AIGaAs/GaAs HEMT process. Successful operation at data rates up to lOGbit/s has been demonstrated.

Long Wavelength Characterization of Internal Quantum Efficiency in LT-GaAs MSM Photodiodes

ABSTRACTMetal-Semiconductor-Metal (MSM) photodiodes fabricated from low temperature (LT) grown GaAs by molecular beam epitaxy have been characterized for wavelengths extending out to 1.5μm. External quantum efficiencies on the order of 0.5 % have been measured for subbandgap wavelengths, which translates to internal quantum efficiencies of 2–4 % for the interdigitated electrode structure with lμm finger spacing and width. Although the effective lifetime of the LT-GaAs has been determined to be <1ps, an MSM photodiode response of ∼10ps full width at half maximum was measured by correlation techniques at 820 nm wavelength, and a system limited response of 3GHz was measured at 1.3 μm wavelength. These experimental results will be described in detail.

A simple 8*8 optoelectronic crossbar switch

The authors demonstrate the operation of an 8*8 optoelectronic crossbar switch consisting of integrated arrays of eight 1*8 GaAs metal-semiconductor-metal (MSM photodiodes connected in a current summing network to the input of Si bipolar transimpedance amplifiers. The MSM devices are also connected to TTL transistor-transistor logic) driven CMOS analog multiplexers which, in the 'off' state, switch the detectors into an open-circuit mode. This particular combination of detectors and switching network gives a very high interchannel isolation, reduced circuit complexity, and low input noise. Data rates of 200 Mbit's and switch reconfiguration times of -100 ns are achieved. System noise is calculated and measured, and the advantages of using fully integrated GaAs crossbar switch arrays are quantitatively discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analysis of picosecond and subpicosecond MSM photodiodes with very low bias voltage

Recently, 4.8-ps FWHM current pulses were generated with a 10- mu mm*15- mu GaAs metal-semiconductor-metal photodiode at a bias voltage of only 0.5 V. To explain this surprising result a full computer simulation was carried out to determine the pulse response as a function of the applied voltage. The simulations are in good agreement with the experiment and allow quantification of the contribution of various parameters to the pulse width. They also show that the photodiode can be used as subpicosecond sampling gate, even without the occurrence of a subpicosecond recombination mechanism, owing to the short diffusion relaxation time. A method is proposed for identifying the electron and hole currents in the photodiode by comparing the pulse response with the autocorrelation signal.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>