Influence of photonic crystals on the performance parameters of GeSn vertical-structure photodiodes

Abstract

In recent years, use of photonic crystals has been recognized as a viable approach to resolve the contradiction between operating speed and light absorption in vertical-structure photodiodes. In this paper, we present a photonic crystal that enhances the responsivity of a GeSn pin photodiode in the near-infrared region of the spectrum. Additionally, the effects of this photonic crystal on the most important properties of the GeSn photodiodes are studied. Based on measurement and analysis of the device’s dark current, responsivity, and speed characteristics, the photonic crystal structure reduces the dark current by approximately 57%, increases the responsivity at 1550 nm and 1650 nm by factors of 2.4 and 3.9, respectively, and increases the 3dB bandwidth at 1550 nm by a factor of approximately 2.6. These results demonstrate that photonic crystals have good application value for solution of the contradiction between the light absorption and operating speed characteristics of high-speed photodiodes.