High-speed lateral polysilicon photodiodes

Abstract
A high-performance lateral p-n photodiode in LPCVD polysilicon has been successfully fabricated and characterized. The device is shown to have a response time of 30 ps, i.e. a 3 dB cut-off frequency of 5.3 GHz, which we believe is the fastest speed reported in polysilicon. The measured device speed is analysed quantitatively on the basis of the recombination-dominated-response model. In so doing, an analytic expression for the impulse response function of such devices is given here for the first time. The general features of the device and its possible applications in optoelectronic integrated circuits are also discussed.