研究目的
To achieve a very low dark current density and a high responsivity with a small Germanium photodiode pitch for uncooled detectors in the near-infrared (NIR) and short-wave infrared (SWIR) ranges.
研究成果
The study demonstrates that a thick Germanium layer on silicon can be used as an active layer in P-i-N photodiodes, achieving low dark current density and high responsivity values suitable for infrared photodetectors in the 1200–1700 nm wavelength range. The tensile strain in the Germanium epilayer enables light detection up to 1700 nm. Future optimizations could include the use of an antire?ective coating and back-side illumination to further enhance performance.
研究不足
The study focuses on photodiodes with a small diameter of 10 μm, which may limit the applicability of the findings to larger devices. Additionally, the high re?ection coefficients due to the metallic electrode and SiO2 passivation layer could be optimized further.
1:Experimental Design and Method Selection:
The study involved the fabrication and characterization of vertical P-i-N photodiodes with the epitaxy of Germanium on Silicon. The Germanium epilayer was designed with specific doping levels for the P-type and N-type layers.
2:Sample Selection and Data Sources:
The samples were 200 mm diameter, ?100? oriented p-type wafer with a Germanium film grown in three steps.
3:List of Experimental Equipment and Materials:
Equipment included an Epi Centura reduced pressure chemical vapor deposition (RPCVD) tool, a M-2000DI spectroscopic ellipsometer, an Empyrean x-ray diffractometer/re?ectometer, and a Renishaw InVia microscope. Materials included GeH4, B2H6, and phosphorus ions for doping.
4:Experimental Procedures and Operational Workflow:
The Germanium film was grown in three steps, followed by phosphorus ion implantation and annealing to define the N+ region. Electrical and optical characterizations were performed.
5:Data Analysis Methods:
Data analysis included the use of spectroscopic ellipsometry, x-ray diffraction, Raman spectroscopy, and electrical characterization techniques to assess the properties of the Germanium epilayer and the performance of the photodiodes.
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