Low-voltage Si-Ge avalanche photodiode

Abstract

Here we report a Si-Ge avalanche photodiode (APD) with a breakdown voltage of only -9.8V. The highest measured bandwidth is 12GHz at gain of 15 giving a 180GHz gainbandwidth product at 1550nm wavelength.

Interface electric field confinement effect of high-sensitivity lateral Ge/Si avalanche photodiodes

“…The research interest on high-performance Avalanche PhotoDiodes (APDs), which exhibit an internal carrier multiplication mechanism caused by internal avalanche gain [1][2][3][4][5] , has been increasing with the development of optical fiber communication. APDs must have a very low noise and a high response to increase sensitivity in low-light-level detection.…”

“…The electron impact ionization rate of Si is 100 times larger than the hole impact ionization rate; hence, using Si as the multiplication material can result in a higher gain and a very low excess noise during detection [6,7] . Ge APDs based on a high-quality Ge epitaxy on Si can easily detect the weak signals in the near-infrared wave band, which includes the 1.55 m wavelength used for fiber communication [4,5,8,9] . Ge APDs are easy to realize on a Si substrate because of the similarities in the crystal structure of Ge and Si.…”

High gain-bandwidth product Ge/Si tunneling avalanche photodiode with high-frequency tunneling effect

“…With the development of optical fiber communications and the continuing expansion of optical-fiber networks, researchers are now focused on high performance near infrared photo detectors for long distance optical communications [1,2] . With their ability to amplify optical signals without an external circuit and thereby improve the signal-to-noise ratio, Ge/Si avalanche photo diodes (APDs) in which the inner gain is generated by avalanche ionization have excellent performance in the detection of weak infrared optical signals, including in the 1.55 μm band, which greatly increases the optical signal propagation distance [3][4][5] . Advantages in cost and integration have also caused researchers to focus on Si based group-IV avalanche photodetectors [6] .…”