Heterogeneous Integrated III-V-on-SOI Photodetector Using Micro-transfer Printing Method

【Objective】Silicon-based optoelectronic platforms have the advantages of low-cost manufacturing, high integration density, and high transmission speed. However, due to the photoelectric properties of silicon materials, it is difficult for monocrystalline silicon to directly achieve high responsivity detection in the O/C band of optical fiber communication. InP-based InGaAs material has an absorption coefficient of 1.0×10 cm^-2 in the O/C band of optical fiber communication, which can be used as an active photodetector with high absorption efficiency. Therefore, the combination of InGaAs/InP active devices and silicon-based waveguides through heterogeneous integration is a feasible direction to achieve high-efficiency photodetectors based on silicon photonic platforms. The large lattice mismatch and the difference in thermal expansion coefficient make it hard to achieve large-scale integration through epitaxial growth technology. The micro-transfer printing technology in bonding integration technology can achieve integration on the micron scale, thereby enabling low-cost, high-efficiency preparation of heterogeneous integrated devices. In the existing preparation process of this technology, the scheme of separating the device from the substrate by etching the sacrificial layer requires extremely high process accumulation. The purpose of this paper is to realize the direct bonding integration of InGaAs/InP Avalanche Photodetector Device (APD) and Silicon on Insulator (SOI) Grating Coupler (GC) by micro-transfer method while retaining the original substrate of the detector.【Methods】This paper studies the basic principle of micro-transfer printing method and builds a micro-transfer printing experimental platform. The heterogeneous integration of the III-V APD sample and the GC on the SOI wafer is realized by the micro-transfer method. The feasibility of the micro-transfer method is evaluated based on the test results.【Results】The response bandwidth of the heterogeneous integrated photodetector obtained by micro-transfer integration is about 4 GHz, and the dark current is about 13 nA (@-13 V), which is basically consistent with the performance test data before the integration of the sample. Affected by the coupling loss, the responsivity of the integrated structure is 7.3×10^-3 A/W (@-25 V). After eliminating the loss of the input fiber-GC, the responsivity of the integrated device is about 1.8×10^-2 A/W (@-25 V).【Conclusion】The work of this paper verifies the feasibility of heterogeneous integration of III-V APD and SOI waveguide platforms based on micro-transfer method. By retaining the InP substrate, the micron-scale × micron-scale APD and SOI GC are directly bonded and integrated through the van der Waals force between the InP substrate/silicon-based photonic platform interface. In this way, we simplify the implementation process of the micro-transfer process with improved integration efficiency. It can be verified by experiments that the dark current and bandwidth performance of the devices before and after integration remain basically unchanged.