High-Temperature Operation of InGaAs/Si Avalanche Photodiodes Enabled by Microcrystalline Ge Interlayer with Optically Tunable Punch-Through Voltage

We present a high-performance InGaAs/Si avalanche photodiode (APD) enabled by heterogeneous bonding using a microcrystalline Ge interlayer. The bonding interface achieves void-free, oxide-free, and robust III–V/Si integration, minimizing interface defects and thermal stress. The APD exhibits responsivities of 42 A/W and 33.8 A/W with gains of 24.06 and 38.32 at 1310 and 1550 nm, respectively, outperforming Ge/Si and InGaAs devices. Notably, an optically tunable punch-through voltage is observed, attributed to space-charge modulation caused by hole trapping in potential wells at the bonded interface. The device maintains stable photoresponse up to 470 K. These results highlight its potential for LIDAR, thermal sensing, and integrated photonics.