Self assembled quantum dot mid-infrared Si/Ge photodetector fabricated by pulsed laser deposition

A Multilayered mid-infrared Si/Ge quantum-dot photodetector is fabricated by pulsed laser deposition. Forty successive Ge quantum dot layers, each covered with a thin Si layer, are deposited. Deposition was monitored by in situ reflection-high energy electron diffraction. The size distribution of the quantum dots was characterized by ex situ atomic force microscopy. I-V measurements reveal typical diode characteristics, while responsivity measurements show an absorption peak around 2 mu m wavelength. Noise variation with applied voltage and corresponding detectivity were also measured.