Performance comparisons between PIN and APD photodetectors for use in optical communication systems

We demonstrate butt-coupled p-i-n InGaAs photodetectors epitaxially grown on silicon substrates by MOCVD. We measure a dark current of 8 nA upon −1V and open eye-diagrams at 15Gb/s upon −3V and at 20Gb/s upon −5V.

Epitaxial III–V-on-silicon waveguide butt-coupled photodetectors

In this letter, we developed an analytical equivalent circuit model, which includes the resistance-capacitance-delay time and carrier transport time, to investigate the distinct dynamic performance of the near-ballistic uni-traveling-carrier photodiode (NBUTC-PD). This device, in which the structure of the collector of the UTC-PD is modified, can achieve excellent performance at a 1.55-/spl mu/m wavelength. According to the measured frequency responses of the scattering (S) parameters of NBUTC-PD and detailed device-modeling, the observed significant reduction of the device capacitance and the enhancement of the net optical-to-electrical bandwidth under high-power operation can be attributed to the unique near-ballistic-transport property of the photogenerated electron, which has never been observed in the traditional high-speed high-power photodiode.

Analytical modeling of a high-performance near-ballistic uni-traveling-carrier photodiode at a 1.55-/spl mu/m wavelength

A time-delay equivalent-circuit model of ultrafast p-i-n photodiodes (PDs) is proposed to describe the operation at high-input power levels. This model includes both the carrier transit-induced time-delay effect and stored charge effect of p-i-n PDs in high-power operation. These effects were represented as a linear RC circuit and capacitance, respectively, both combined in parallel to a voltage-controlled current source. The validity of this model was confirmed with good curve fitting to the measured optical-frequency responses of an ultrafast side-illuminated p-i-n PD.

A time-delay equivalent-circuit model of ultrafast p-i-n photodiodes

We investigate the area-dependent characteristics of photodetection frequency responses of 850-nm silicon avalanche photodetectors (APDs) fabricated with standard complementary metal-oxide-semiconductor (CMOS) technology. CMOS-compatible APDs (CMOS-APDs) based on a p+/n-well junction with four different device areas are used for the investigation, and we identify factors that influence photodetection frequency responses with the goal of achieving optimal photodetection bandwidth performance. Their current-voltage characteristics, electrical reflection coefficients, and photodetection frequency responses are measured, and the characteristics of the CMOS-APD photodetection frequency responses are analyzed using equivalent circuit models. From this, it is clarified how the four different factors of photogenerated-carrier transit time, device RC time constant, inductive-peaking effect, and parasitics contribute to the photodetection frequency responses and how their contribution changes with device areas. Among the four types of CMOS-APDs investigated in this study, the 10 × 10 μm2 CMOS-APD has the largest 3-dB photodetection bandwidth of 7.6 GHz.

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Area-Dependent Photodetection Frequency Response Characterization of Silicon Avalanche Photodetectors Fabricated With Standard CMOS Technology

A novel small-signal radio frequency (RF) equivalent-circuit of the side-illuminated input tapered waveguide-integrated p-i-n photodiodes (WG PIN PD) is proposed. The proposed RF equivalent-circuit involves both the carrier-transit effect and the external resistance-capacitance (RC) time constant limitation on the frequency response of the p-i-n PD. The carrier-transit effect is realized by adding an RC circuit to an ideal voltage-controlled current source as the input opto-RF equivalent circuit. The carrier transit-time effect is equivalently represented by the time-constant of this input RC circuit. This new equivalent circuit model fits well with both the measured reflection and optoelectronic conversion parameters of the WG PIN PD in a broad frequency range from 45 MHz to 50 GHz.

M. Kobayashi

Papers

Analysis of high speed p-i-n photodiode S-parameters by a novel small-signal equivalent circuit model

A time-delay equivalent-circuit model of ultrafast p-i-n photodiodes