SBIR-STTR Award

The goal of the project is to develop a novel separate absorption and charge multiplication (SACM) avalanche photodiode (APD) operating at wavelengths of 2 um and even longer. The proposed APD can achieve high performance at significantly low cost using GeSn absorber material grown by an industry manufacture chemical vapor deposition reactor and a foundry material growth operation mode. It targets to be used in eye-safe and low-cost LIDAR systems. The key enabling factors for the new APD over current sensors for LIDAR applications are based on two appealing GeSn material properties: whole short-wave infrared (SWIR) range and even longer wavelength coverage using band-to-band transitions; material growth below 400° C for full complementary metal–oxide–semiconductor (CMOS) compatibility. The key concepts of the proposed SACM GeSn APD are: i) utilizing GeSn as the front-end light absorber due to the high absorption beyond Ge band edge by incorporating Sn to cover the whole SWIR band; ii) utilizing the excellent multiplication property of Si with the low ionization ratio for low excess noise; iii) leveraging mature Ge/Si SACM APD design; iv) leveraging the recent advances of GeSn material development accomplished by the world leading experts in the team. In Phase I, the team focuses on feasibility study of the proposed GeSn/Si APD. The work plan includes: i) modeling GeSn photodiode (PD) and APD devices, since high performance GeSn PD is the foundation of GeSn APD and effective modeling is the foundation of high performance GeSn PD; ii) evaluating material growth and characterization feasibility for basic APD building blocks; iii) evaluating developing strategy for high performance GeSn PD and specially forming strategy to achieve low dark current; iv) evaluating GeSn APD development strategy to build surface illuminated and waveguide based devices; v) developing Phase II working schedule to accommodate the foundry material growth operation mode.

In this project, Akrtonics proposes to develop a novel Si based revolutionary infrared sensor technology potentially offering monolithic integration of CMOS circuits with a high-performance detector array made from an emerging group-IV alloy.  The proposed sensing materials, SiGeSn semiconducting alloys, have spectral sensitivity that potentially covers a broad wavelength range from SWIR, MWIR, to LWIR.  The resulted sensor array could be manufactured using standard IC industry techniques for high volume production, high reliability, and low cost.  The technology could be disruptive for our targeted markets such as autonomous driving and IR imaging.  The enabled LiDAR/LADAR solution for autonomous driving offers advantages over the state-of-art including eye safety, range performance, background immunity, atmospheric transmission, reliability, and cost.  The envisioned sensor for IR imaging offers a potential 10,000 fold cost reduction compared with its counter parts using III-V and II-VI materials yet maintains similar performance and can scale up to large array size.  The specifically tailored device structure to be developed in this project is a GeSn/Si avalanche photodiode (APD) using an architecture of separate absorption and charge multiplication.  The proposed research activities include device modeling, high quality material growth, and high performance GeSn PD and APD development.