New photodetector offers sensitive broadband detection and low power consumption

Photodetectors that are highly sensitive to a wide range of wavelengths find extensive use in applications such as cameras, fiber-optic telecommunications and biosensing. These detectors typically require low power consumption and must be compatible with silicon chip fabrication processes. A new photodetector looks to provide these features and is poised to be an effective alternative for broadband detection of visible to near-IR light.

Siontas et al. demonstrated the use of a new germanium-based photodetector capable of broadband detection at room temperature, and its fabrication was relatively simple, using nanostructured germanium in the form of quantum dots. The devices exhibited internal gain and were capable of detecting light, from the visible up to the near-infrared 1,550-nanometer telecom wavelength, with significantly greater sensitivity than commercially available silicon and germanium photodiodes.

The device yielded high performance even when operated at -5 and -2 volts, showing sensitivity higher than common silicon and germanium photodetectors. For conventional photodetectors to exhibit such high sensitivity, they would need orders of magnitude higher voltages, which would compromise the device’s energy efficiency, said Siontas.

Such leaps in efficiency translate to less reliance on large, cumbersome power supplies or the need for cryogenic cooling, providing a way forward for portable broadband photodetectors that work at room temperature. Siontas said he hopes the detector will provide a stepping stone to the group’s ultimate goal of building an integrated biosensing device based on a plasmon-enabled interferometer for glucose sensing.

Source: “Broadband visible-to-telecom wavelength germanium quantum dot photodetectors,” by Stylianos Siontas, Haobei Wang, Dongfang Li, Alexander Zaslavsky, and Domenico Pacifici, Applied Physics Letters (2018). The article can be accessed at https://doi.org/10.1063/1.5052252 .