A high-responsivity photodetector absent metal-germanium direct contact

Abstract

We report a Ge-on-Si photodetector without doped Ge or Ge-metal contacts. Despite the simplified fabrication process, the device shows a responsivity of 1.14 A/W at -4 V reverse bias and 1.44 A/W at -12V, at 1550 nm wavelength. Dark current is less than 1µA under both bias conditions. We also demonstrate open eye diagrams at 40Gb/s.

High-Responsivity Low-Voltage 28-Gb/s Ge p-i-n Photodetector With Silicon Contacts

“…The Si-LPIN photodetector has a responsivity higher than 1.0 A/W in the whole wavelength range, which is much higher than that measured from the BL-VPIN device (0.4-0.6 A/W). This is among the best results that have been published for Ge WPDs [2]- [4], [7]- [9].…”

“…They have been extensively researched, and various device structures have been developed [1]- [9]. Waveguide photodetectors are advantageous over surface illuminated photodetectors owing to their ability to create longer absorption lengths without causing a carrier-transit-time limitation to their bandwidth.…”

“…However, this should not impact device speed: for practical applications, 25 Gb/s or even 40 Gb/s under low-voltage operation are typical requirements. Although [8], [9] have demonstrated photodetectors without doping or contacting of germanium, it requires a high bias voltage of -4 V for the devices to achieve an opto-electrical 3 dB bandwidth of ∼20 GHz, which is necessary for photodetectors to receive 25 Gb/s on-off keying (OOK) signals. The high bias voltage of −4 V is however not CMOS compatible.…”

−1 V Bias 56 Gbps Germanium Waveguide p-i-n Photodetector with Silicon Contacts

“…A germanium waveguide p-i-n photodetectors (WPD) is a critical building block in silicon photonics optical interconnects and has been researched extensively [1][2][3][4][5][6][7][8][9]. Conventional germanium WPDs require doping in germanium as well as a metal contact on germanium to form the p-i-n junction.…”

Quantum dot semiconductor optical amplifier/silicon external cavity laser for O-band high-speed optical communications

“…1 Silicon photonics has attracted extensive academic and industrial attention as a solution for nextgeneration high-speed, low-energy consumption, and lowcost communication systems. The last decade witnessed tremendous enrichment and maturation of the silicon photonics device library, including high-performance passive components, [2][3][4] silicon modulators, 5 germanium on silicon photodetectors, 6,7 and hybrid integrated lasers. [8][9][10][11] Almost all silicon photonics devices demonstrated to date operate in the Cband (1530 to 1565 nm), which is within the fiber loss and erbium amplification window and is ideal for longhaul communications.…”