Measurement and modelling 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 measurements. 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 behaviour 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 (similar to0.6 V) than the previous process (similar to4 V) for an identical layout geometry. Preliminary high-speed measurements of the newer devices are quite encouraging.