E. Droge

65 GHz InGaAs/InAlGaAs/InP waveguide-integrated photodetectors for the 1.3–1.55 μm wavelength regime

We report on ultrafast waveguide-integrated metal-semiconductor-metal photodetectors based on low pressure metal organic chemical vapor deposition grown semiinsulating InP/InGaAs/InAlGaAs/InP layers. The vertically coupled detectors have an internal coupling efficiency of >90% at 1.3 and 1.55 μm wavelength for detector lengths of 30 μm. A 3 dB bandwidth of 65 GHz at 1.55 μm wavelength is achieved by employing 0.3 μm feature-size finger electrodes and an active layer thickness of 150 nm. Furthermore, we present results on high-performance devices with a buried waveguide structure fabricated by regrowth of InP:Fe.

Transient response of lateral photodetectors

A two‐dimensional physical device model for characterizing the transient operation of lateral photodetectors is presented. It is based upon a corpuscular approach where the impulse response is constituted by the superposition of a large number of photocurrent pulses originating from spatially distributed discrete electron‐hole pairs generated by an optical impulse. The motion of photogenerated carriers and the resulting photocurrent pulses in the external circuit are related by Ramo’s theorem which is shown to be fundamental for gaining a correct understanding of the time response of lateral detectors. The accuracy of the predictions obtained from the modeling is underpinned by their excellent agreement with experimental data on the impulse response of InP:Fe/InGaAs:Fe metal‐semiconductor‐metal detectors.

Distributed waveguide-integrated InGaAs MSM photodetectors for high-efficiency and ultra-wideband operation

A considerable improvement of bandwidth and efficiency of monolithically integrated distributed InGaAs MSM photodetectors is reported. From a thorough modeling, design criteria for the structural parameters of the optical waveguide and absorber as well as the electrical transmission line are derived which permit the optimization of the quantum efficiency for ultrawideband operation (100-200 GHz). Our experimental results are in very good agreement with the model. Distributed detectors incorporating a ridge waveguide structure embedded in regrown InP are additionally demonstrated to significantly reduce the optical loss of previously reported devices.

Waveguide-integrated InP/InGaAs/InAlGaAs MSM photodetector for operation at 1.3 and 1.55 /spl mu/m

High-speed multi-wavelength waveguide-integrated metal-semiconductor-metal (MSM) photodetectors based on MOCVD grown InP/lnGaAs/InAlGaAs layers are reported. The evanescent field coupled detectors have an absorbing layer thickness of only 150 nm and an electrode feature size as small as 0.3 /spl mu/m. An internal coupling efficiency of /spl ges/90% has been achieved for detector lengths as short as 20 /spl mu/m and 30 /spl mu/m at 1.3 and 1.55 /spl mu/m wavelength, respectively. A 3-dB bandwidth of 50 GHz at 1.55 /spl mu/m wavelength has been obtained.

Large area InGaAs MSM photodetectors

The authors report on high-performance InGaAs metal-semiconductor-metal (MSM) photodetectors for large area applications. Fe-doping was employed to obtain the high-resistivity InGaAs:Fe photoactive layer and the InP:Fe Schottky-barrier enhancement layer. The fabricated interdigitated MSM detectors have an active area of 350 /spl mu/m /spl times/ 350 /spl mu/m. At typical operating bias of 10 V, a capacitance of 1.6 pF and almost 1 GHz electrical bandwidth was achieved. The devices are very attractive for large area photoreceivers since they consume high-sensitivity and large-bandwidth operation due to low capacitive loading.<<ETX>>

Distributed millimeter-wave InGaAs metal-semiconductor-metal photodetector

A 78-GHz traveling-wave photodetector for the long-wavelength range has been realized by periodically distributing four InGaAs-InP metal-semiconductor-metal detectors with sub-half-micrometer feature size electrodes on top of an InAlGaAs-core optical waveguide.