$128\times 128$ InGaAs/GaAs Strained-Superlattice Photodiode Arrays for 1064 nm NIR Detection

High-performance proof-of-concept $128 \times 128$ InGaAs/GaAs strained-layer superlattice (SLS) photodiode (PD) array, featuring 8 × 8 $\mu \text{m}^{2}$ pixels with 2 $\mu \text{m}$ interpixel gap, is demonstrated for efficient 1064 nm detection. The SLS photoabsorber design parameters are engineered using a calibrated 8-band $\mathbf {k} \cdot \mathbf {p}$ Schrödinger-Poisson solver, while Sentaurus-TCAD simulations guide device-level optimization for low dark-current, fast response, $\sim$75% quantum efficiency, and low-bias operation. Initial design implementations with conventional vertical sidewall mesas exhibit $\sim$60% surface leakage contribution in dense arrays. A quantum-well-intermixed tapered sidewall mesa (QWI-TSM) architecture, developed here using a low-thermal-budget Ar plasma-induced intermixing, and SU-8 passivation has helped devices reduce the surface current density contribution down to 14%. The fabricated arrays exhibit a dark current of 9 nA and QE $\sim$60% at $-1$ V, approaching commercial 1064 nm PD performance, with further gains expected through improved epitaxy. These results validate the proposed scalable InGaAs/GaAs SLS PD arrays for next-generation high-performance 1064 nm near-infrared imaging and sensing.