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Theoretical Calculation and Experimental Verification for Dislocation Reduction in Germanium Epitaxial Layers with Semicylindrical Voids on Silicon
Published on: July 17, 2020
Strained germanium thin film membrane on silicon substrate for optoelectronics
Donguk Nam1, Devanand Sukhdeo, Arunanshu Roy
1Department of Electrical Engineering, Stanford University, Stanford, California 94305, USA. dwnam@stanford.edu
Optics Express
|January 26, 2012
Summary
Researchers developed a new method to apply sustainable biaxial tensile strain to Germanium (Ge) membranes, enhancing light emission and paving the way for efficient photodetectors.
Area of Science:
- Materials Science
- Semiconductor Physics
- Optoelectronics
Background:
- Germanium (Ge) is a crucial semiconductor material for optoelectronic applications.
- Achieving significant tensile strain in Ge is challenging but offers potential for improved performance.
- Existing methods for straining Ge often lack sustainability or scalability.
Purpose of the Study:
- To present a novel and sustainable method for inducing large biaxial tensile strain in thin Ge membranes.
- To investigate the effects of this strain on the electronic and optical properties of Ge.
- To demonstrate the potential of strained Ge in advanced photodetector applications.
Main Methods:
- Integration of a stressor layer on a Silicon (Si) substrate to introduce biaxial tensile strain in a Ge membrane.
- Raman spectroscopy for precise strain measurement.
- Photoluminescence spectroscopy to analyze band gap changes and emission efficiency.
- Device fabrication and characterization of highly strained Ge photodetectors.
- Computational simulations to predict carrier behavior under strain and doping.
Main Results:
- Successfully introduced sustainable biaxial tensile strain exceeding 1% (1.13%) in a thin Ge membrane.
- Observed a direct band gap reduction of 100 meV, leading to enhanced light emission efficiency.
- Simulations predicted that 1.1% strain combined with heavy n(+) doping reduces the carrier density for population inversion by over 60 times.
- Demonstrated the first highly strained Ge photodetector with excellent responsivity beyond 1.6 µm.
Conclusions:
- The novel method enables significant and sustainable biaxial tensile strain in Ge membranes.
- Strained Ge exhibits a reduced band gap and enhanced light emission, crucial for optoelectronic devices.
- The combination of strain and doping shows great promise for reducing the threshold for population inversion, enabling efficient light sources.
- Highly strained Ge is a viable material for high-performance photodetectors operating at longer wavelengths.
