Equivalent Circuit Model for InP-based Uni-Traveling-Carrier Photodiodes with Dipole-doped Structure

Abstract

An equivalent circuit model has been proposed to analyze the high performance of InPbased uni-traveling-carrier photodiodes (UTC-PDs) with novel dipole-doped structure. The validity of this model has been confirmed with experimental data.

Characterization of high‐photocurrent and high‐speed INP‐based uni‐traveling‐carrier photodiodes at 1.55‐μm wavelength

“…A typical InP‐based UTC‐PD consists of a p‐type narrow‐bandgap InGaAs light absorption layer and an n‐type wide‐bandgap InP carrier collection layer . The abrupt energy barrier at InGaAs/InP interface blocking electron flow and causing a buildup of stored charge would degrade DC performance at high current densities and also limit the high‐speed performance of PD.…”

“…The abrupt energy barrier at InGaAs/InP interface blocking electron flow and causing a buildup of stored charge would degrade DC performance at high current densities and also limit the high‐speed performance of PD. To overcome this problem, a dipole‐doped structure, which consists of a p‐type doped 8‐nm InGaAs, a n‐type doped 8‐nm InP layer and a 22‐nm undoped InGaAs setback layer, was inserted between the InGaAs absorption layer and InP collection layer to suppress the current blocking effect . The epi‐layer structure could be found in Table .…”

“…To overcome this problem, a dipole‐doped structure, which consists of a p‐type doped 8‐nm InGaAs, a n‐type doped 8‐nm InP layer and a 22‐nm undoped InGaAs setback layer, was inserted between the InGaAs absorption layer and InP collection layer to suppress the current blocking effect . The epi‐layer structure could be found in Table . The effectiveness of the dipole‐doped structure has been validated by a 3‐dB bandwidth of more than 20 GHz (limited by measurement equipment) and a high‐photocurrent of 160 mA achieved from a 12‐µm‐diameter and a 70‐µm‐diameter fabricated InP‐based dipole‐doped UTC‐PD respectively .…”

“…The epi‐layer structure could be found in Table . The effectiveness of the dipole‐doped structure has been validated by a 3‐dB bandwidth of more than 20 GHz (limited by measurement equipment) and a high‐photocurrent of 160 mA achieved from a 12‐µm‐diameter and a 70‐µm‐diameter fabricated InP‐based dipole‐doped UTC‐PD respectively . The dipole‐doped structures used in this work were grown by molecular beam epitaxy (MBE).…”

“…Comparing with previous literatures , current method has the following advantages: The equivalent circuit model is developed basing on actual device structure and physics. The dipole‐doped structure at the InGaAs/InP heterostructure interface has been taken into account in the equivalent circuit model to simulate its effectiveness on suppressing the current blocking effect . Most of the circuit component parameters, including parasitic and intrinsic parameters, can be extracted directly from a set of closed‐form expressions based on the measured reflection coefficients ( S 22 ) and frequency responses ( S 21 ) of devices. Only one parameter (capacitance of the dipole‐doped structure C dd ) cannot be extracted directly by using analytical method. It is obtained by using optimization method.…”