Deposited low temperature silicon GHz modulator

TL;DR

This paper presents a novel deposited low-temperature silicon GHz modulator using polycrystalline silicon, enabling CMOS-compatible, high-performance electro-optic devices on various substrates, expanding silicon photonics applications.

Contribution

Introduces a deposited polysilicon platform for GHz silicon photonics, compatible with CMOS processes and flexible substrates, overcoming limitations of traditional SOI-based photonics.

Findings

Demonstrated a 3 Gbps polysilicon electro-optic modulator.

Achieved high optical quality in deposited polysilicon suitable for high-performance devices.

Showcased compatibility with CMOS backend processes.

Abstract

The majority of silicon photonics is built on silicon-on-insulator (SOI) wafers while the majority of electronics, including CPUs and memory, are built on bulk silicon wafers, limiting broader acceptance of silicon photonics. This discrepancy is a result of silicon photonics's requirement for a single-crystalline silicon (c-Si) layer and a thick undercladding for optical guiding that bulk silicon wafers to not provide. While the undercladding problem can be partially addressed by substrate removal techniques, the complexity of co-integrating photonics with state-of-the-art transistors and real estate competition between electronics and photonics remain problematic. We show here a platform for deposited GHz silicon photonics based on polycrystalline silicon with high optical quality suitable for high performance electro-optic devices. We demonstrate 3 Gbps polysilicon electro-optic modulator fabricated on a deposited polysilicon layer fully compatible with CMOS backend integration. These results open up an array of possibilities for silicon photonics including photonics on DRAM and flexible substrates.