Alexandre Pauchard

Fused InGaAs-Si avalanche photodiodes with low-noise performances

A fused InGaAs-Si avalanche photodiode (APD) with a low excess noise factor of 2.3 at a gain of 20 is reported. This corresponds to a k factor of 0.02 for the silicon avalanche region. Dark current density as low as 0.04 mA/cm/sup 2/ at -5 V and 0.6 mA/cm/sup 2/ at a gain of 10 are measured; a small thermal coefficient, 0.09%//spl deg/C, of the breakdown voltage is observed for this APD.

Frequency response and bandwidth enhancement in Ge/Si avalanche photodiodes with over 840GHz gain-bandwidth-product

In this work we report a separate-absorption-charge-multiplication Ge/Si avalanche photodiode with an enhanced gain-bandwidth-product of 845 GHz at a wavelength of 1310 nm. The corresponding gain value is 65 and the electrical bandwidth is 13 GHz at an optical input power of -30 dBm. The unconventional high gain-bandwidth-product is investigated using device physical simulation and optical pulse response measurement. The analysis of the electric field distribution, electron and hole concentration and drift velocities in the device shows that the enhanced gain-bandwidth-product at high bias voltages is due to a decrease of the transit time and avalanche build-up time limitation at high fields.

Epitaxially-grown Ge/Si avalanche photodiodes for 1.3µm light detection

We designed and fabricated Ge/Si avalanche photodiodes grown on silicon substrates. The mesa-type photodiodes exhibit a responsivity at 1310nm of 0.54A/W, a breakdown voltage thermal coefficient of 0.05%/°C, a 3dBbandwidth of 10GHz. The gain-bandwidth product was measured as 153GHz. The effective k value extracted from the excess noise factor was 0.1.

Monolithic Ge/Si avalanche photodiodes

We demonstrate mesa-type and waveguide-type Ge/Si avalanche photodiodes both with high performances. The gain-bandwidth product was measured as high as 340GHz and the receiver sensitivity was −28dBm and −30.4dBm for mesa-and waveguide-type devices, respectively.

Infrared-sensitive InGaAs-on-Si p-i-n photodetectors exhibiting high-power linearity

We report on the device fabrication and measured performance of p-i-n photodiodes made from wafer-bonded InGaAs-on-Si material. Dark currents below 38 pA and 3-dB bandwidths above 11 GHz were measured for a -4-V bias and for an active area diameter of 20 /spl mu/m. The thermal conductivity of silicon enables a 200-MHz 1-dB compression current of 76.5 mA, measured on nonoptimized test devices. These devices dissipate upwards of 612 mW of electrical power. High-yield wafer-scale fabrication of InGaAs-on-Si p-i-n photodetectors is demonstrated.

Dark current reduction in fused InGaAs/Si avalanche photodiode

Mesa type fused InGaAs/Si separated absorption and multiplication APDs with a diameter of 130 /spl mu/m have been fabricated on n-type Si substrate. Substantial dark current reduction has been achieved compared with the published data for fused InGaAs/Si APDs. Dark current densities as low as 0.23 mA/cm/sup 2/ at -5 V and 3 mA/cm/sup 2/ at a gain of 10 are reported. Our improved dark current even though is still 2 orders larger than the conventional mesa-structure InGaAs/InP APD lower excess noise level is expected due to the larger difference between the electron and hole ionization coefficients of Si.

Wafer-bonded InGaAs/silicon avalanche photodiodes

Wafer-bonded avalanche photodiodes (APDs) combining InGaAs for the absorption layer and silicon for the multiplication layer have been fabricated. The reported APDs have a very low room-temperature dark current density of only 0.7 mA/cm2 at a gain of 10. The dark current level is as low as that of conventional InGaAs/InP APDs. High avalanche gains in excess of 100 are presented. The photodiode responsivity at a wavelength of 1.31 micrometers is 0.64 A/W, achieved without the use of an anti-reflection coating. The RC-limited bandwidth is 1.45 GHz and the gain-bandwidth product is 290 GHz. The excess noise factor F is much lower than that of conventional InP-based APDs, with values of 2.2 at a gain of 10 and 2.3 at a gain of 20. This corresponds to an effective ionization rate ratio keff as low as 0.02. The expected receiver sensitivity for 2.5 Gb/s operation at (lambda) = 1.31 um using our InGaAs/silicon APD is -41 dBm at an optimal gain of M = 80.

High-performance InGaAs-on-silicon avalanche photodiodes

We have demonstrated a high-performance InGaAs-on-silicon APD that exhibits a very low dark current density of 0.7 mA/cm/sup 2/, high avalanche gain (M/spl Gt/100), an RC-limited bandwidth of 1.45 GHz, and a gain-bandwidth product of 290 GHz. We estimate that our device can achieve a sensitivity improvement of 5 dB compared to state-of-the-art InP-based APD receivers. We are currently measuring the APD excess noise factor. We will report this measurement at the conference.

Origin of the gain-bandwidth-product enhancement in separate-absorption-charge-multiplication Ge/Si avalanche photodiodes

A separate-absorption-charge-multiplication Ge/Si avalanche photodiode with very high gain-bandwidth-product over 800GHz is reported. The origin of this dramatically high value is explained using well consentient measurement and simulation results.

Wafer bonding for the fabrication of high-performance photodetectors: a mature technology ?

Summary form only given. Significant progress has been achieved towards the demonstration of direct wafer bonded photodetectors. This device design approach offers the freedom to combine dissimilar materials in order to fabricate novel device structures not obtainable using standard techniques. Significant device performance advantages have been demonstrated in specific device applications using wafer bonding. The results summarized here demonstrate additional progress towards defining wafer bonding as a mature technology - a manufacturable and cost-effective process applied to APDs that portends commercial application.