Modeling and Enhancing Responsivity for the InGaAsN/GaAs Configuration in p-i-n Photodiodes

This paper presents the numerical modeling, simulation, and optimization of a p-i-n photodiode (PD) based on quaternary InGaAsN using the Atlas Silvaco simulator. The proposed architecture incorporates wide-bandgap, transparent GaAs contact layers on both the p and n sides to enhance optical coupling and frequency response characteristics. For the unstrained configuration (In = 6%, N = 2%, ε = 0%, and T = 300 K) with an absorber thickness of d_abs = 1.5 µm under a -2 V reverse bias, the device achieves a peak responsivity R(λ) of 0.339 A/W at a wavelength of 0.975 µm, corresponding to a quantum efficiency (QE) of 43% and a cutoff frequency (F_c) of 11.60 GHz. To evaluate the influence of mechanical strain, a comparative analysis was performed for a strained structure (In = 10%, N = 2%, ε = -0.30%), which exhibited a degraded QE of 38.47%. The simulated results for the unstrained photodiode show strong agreement with benchmark data from the literature. This comparison demonstrates that the proposed strain-free p-i-n PD structure achieves improved optoelectronic performance, supporting its potential for high-speed photodetection applications.