Performance characterization of the defect-enabled all-silicon avalanche photodiode at telecommunication wavelengths

Abstract

Although silicon forms the foundation of the traditional microelectronics industry, the growing demand for higher data transmission capacity and lower energy consumption is propelling the advancement of a complementary technology - Silicon Photonics. It delivers exceptional scalability and power efficiency while enabling low-cost production by leveraging CMOS fabrication facilities and processes. This work describes research on the performance of a fully-integrated, one-material photodetector solution for the Silicon Photonics platform, designed for operation at telecommunication wavelengths, specifically 1550 nm. Following a introductory chapter to place this work into context, Chapter 2 provides a theoretical background of photodetectors and absorption mechanism in silicon. Chapter 3 studies the introduction of defects into silicon waveguides to improve the photodetector efficiency in converting optical signals at 1550 nm. The fabricated devices achieved multiplication gains up to M=35, with gain-bandwidth products reaching 230 GHz, and responsivity as high as 13 A/W. Chapter 4 explores the noise characteristics of these devices and provides a detailed analysis of noise behavior under different operating conditions. The excess noise factor measurements confirmed low-noise avalanche performance with an effective k-value of 0.1, attributed to the dominance of electron-driven carrier multiplication. In Chapter 5, the high-power performance of the detector operating in avalanche mode is studied, particularly the device linearity under high optical power and high electrical RF power input. The device shows one of the highest bandwidth-power product amongst waveguide photodetectors. Chapter 6 conducts a thorough study of the temperature dependency behaviour of the silicon photodetector using integrated on-chip micro-heaters, and experimentally demonstrates an enhanced performance in device sensitivity and noise reduction at elevated temperature relative to room temperature operation. This thesis concludes with Chapter 7, in which a summary of the findings is provided, and suggestion for future work is made.