Achievement of non-charge layer InGaAs/Si avalanche photodiodes by introducing a groove ring at the bonding interface

The avalanche photodiode (APD) is a prototypical example of a fast and high-gain detector, particularly in the infrared band, where it plays a crucial role in both military and civil optoelectronic devices. The combination of indium gallium arsenide (InGaAs) and silicon (Si) offers an ideal solution for achieving high-performance APDs. For traditional InGaAs/Si APDs, the incorporation of a p-Si charge modulation layer between InGaAs and Si is necessary for electric field modulation. This ensures that a high electric field is maintained in the multiplication layer while keeping it low in the absorption layer. However, the preparation of the p-Si charge modulation layer necessitates a tedious and expensive ion implantation process. Besides, the ion implantation process can also lead to material surface contamination that significantly affects the performance of the device. In this paper, an InGaAs/Si APD without the charge layer is reported. This approach is based on semiconductor direct bonding technology, wherein a groove ring is introduced into the bonding interface to replace the charge layer to regulate the electric field distribution. The electric field of the absorption layer and the multiplier layer is controlled by adjusting the number of grooved rings. By introducing 11 grooved rings into the bonding interface, we achieve a remarkable gain bandwidth product of 88.55 GHz. These findings hold significant implications for the future development of non-charge layer InGaAs/Si APDs with high-gain bandwidth products.