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Analysis of Electrical and Optical Characteristics of InP/InGaAs Avalanche Photodiodes in Linear Regime by a New Simulation Environment

The linear characteristics of the InP/InGaAs avalanche detectors are modeled and numerically analyzed by developing a new TCAD-based simulation environment. Temperature dependency of the impact ionization coefficients in InP are fitted for 200 K to 300 K temperature range. Adjustment of the model parameters for the simulations of the dark current sources in InP and InGaAs materials is performed in the same temperature range. Optical constants of the InGaAs material used in the layer stack are fitted to account for the absorption in the material for a range of wavelengths between 0.9 and 1.7 µm. Dark current and I-V characteristics under illumination are simulated and analyzed. Impact of the operating temperature on responsivity, breakdown voltage and dark current are analyzed. Excess noise factor is also calculated. Process simulations of Zn diffusion into InP are included in the TCAD simulator and the impact of the real diffusion profiles on the diode characteristics are assessed. The dark current for the structure with diffused Zn p+ region decreases by a factor of 1.7 compared to the structure with box-like constant concentration p+ region extracted at operating temperature of 200 K at 90% of VBR.

avalanche photodiode; InGaAs; InP; TCAD simulations; electrical characteristics; optical characteristics; TCAD calibration

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