The photodetector of Ge nanocrystals/Si for 1.55 μm operation deposited by pulsed laser deposition

The photodetector properties of a Ge nanocrystals detector fabricated by pulsed laser deposition and in situ rapid thermal annealing treatment at 600 °C have been studied. Strong optical absorption and photocurrent response of the detector are measured in the wavelength range 1.3-1.55 μm. The detector possesses a low dark current of 61.4 nA and a photocurrent responsivity of 56 mA/W at the reverse bias 5 V. The external quantum efficiency at 1.55 μm is estimated to be 15%. The stop wavelength of absorption spectra extends to 1.65 μm. It indicates that these kind of Ge nanocrystals devices can be used as a 1.3-1.55 μm near infrared detector.