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Waveguide Ge-PD Simulation
Jeong-Min Lee
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Ge-PD Simulation Lumerical Device Lumerical FDTD
Current-voltage characteristic Band structure Charge (Jn, Jp, …) Doping (NA, ND, ...) Electrostatics (E, V, …) Mobility (μn, μp, …) Lumerical FDTD Photo-generated carriers
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Ge-PD Structure <Top-view> <Cross-section>
Doping concentration P-type Si: 2x1018 /cm3 (constant doping) i-Ge: 2x1013 /cm3 (constant doping) N-type Ge: ~ 5x1018 /cm3 (diffusion doping)
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Procedure Configure materials Draw & configure 3-D structure of Ge-PD
Draw & configure doping layers P-type, intrinsic, n-type Draw & configure device region Simulation area Define & configure electrical contacts Cathode, anode Device simulation Electric field, dark current simulation FDTD simulation Photo-generated carrier calculation Photocurrent, responsivity simulation
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Material Setting: Ge
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Oxide
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Silicon Substrate
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Silicon Taper
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Ge
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Cathode
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Anode & 5.3 (another anode)
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P-Type Si (Constant Doping)
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Intrinsic Ge (Constant Doping)
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N-Type Si (Diffusion Doping)
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Device Region: Simulation Area
2D simulation (/μm) PD length
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Device Region Setting (Simulation Area)
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Electrical Contact Setting
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Simulation Results: Doping Profile
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Simulation Results: Electric Field Distribution
At VR = 2V
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Simulation Results: Cathode Current (Dark)
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Simulation Results: Anode Current (Dark)
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FDTD: Structure 1. Draw structure
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FDTD Simulation Region
1 2 3 4
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Source (1/2): Mode Source
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Source (2/2): Mode Select
4 3 5
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Generation Rate 1 2 4 5 3 6. Click Run
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Edit Code sourceintensity(f) sourcepower(f)
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Make Generation Rate File
Make ‘CW_generation.mat’ file in working directory
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Device: Import Generation Rate
1 2 3
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Simulation Results: Photocurrent (Cathode)
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Simulation Results: Responsivity
Load ‘Bias vs. Responsivity.lsf’ Run
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Code Bias vs. Responsivity.lsf Pin=1e-3; # Watts
I=-2*getdata("Device region", "anode.I"); V=linspace(0,4,5); Resp=I/Pin; plot(V,I*1e6,"photo detector bias voltage(V)","I_(illumination) uA "); plot(V,Resp,"photo detector bias voltage(V)","Responsivity (A/W) ");
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Exercise Draw same structure of Ge p-i-n PD.
Doping concentration conditions: P-type: 2x1019 /cm3 Intrinsic: 2x1013 /cm3 N-type: 5x1019 /cm3 (ref concentration: 1x1017 /cm3) Plot doping profiles (NA, ND). Plot electric-field profiles at 1- and 4-V reverse bias voltage. Plot dark current, photocurrent, and responsivity according to reverse bias voltages from 0 to 4V.
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