Abstract
The frequency response of a dual depletion p-i-n (PIN) photodiode structure is investigated. It is assumed that the light is incident on the N side and the drift region is located between the N contact and the absorption region. The numerical model takes into account the transit time and the capacitive effects and is applied to photodiodes with non-uniform illumination and linear electric field profile. With an adequate choice of the device’s structural parameters, dual depletion photodiodes can have larger bandwidths than the conventional PIN devices.
Highlights
The photodiode is one of the most important devices in an optical communication system
The frequency response of the dual depletion PIN photodiode is computed by considering the transit time and the capacitive effects
The current source I1 is directly related to the transit time limited frequency response given by (9), and the output current I0 may be expressed as I 0= HRC I1 where HRC is the transfer function associated with the capacitive effects which, neglecting Rd, may be written as
Summary
The photodiode is one of the most important devices in an optical communication system. The materials most commonly used are: InP, for the N and P contact regions, and In0.53Ga0.47As, for the near intrinsic absorption region [1]. The bandwidth-quantum efficiency product is nearly constant for a wide range of absorption region lengths, taking values of the order of tens of GHz. The conventional PIN photodiode is not suitable for the last generation communication systems with high bit rate. In order to increase the device’s bandwidth and the bandwidth-quantum efficiency product, the capacitive effects should be reduced. Towards this goal, a new structure has been proposed which is basically a PIN structure with an additional layer of intrinsic InP next to the absorption layer of InGaAs [4]. The results may be used to optimize the device’s bandwidth regarding its dimensions and bias voltage
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