研究目的
To present a novel experimental PLE system for precision-based quantification of SRH lifetimes and recombination velocities in direct band gap experimental semiconductor materials and devices, and to evaluate surface passivation and intermediate fabrication processes.
研究成果
A novel Xe arc lamp based PLE has been used to characterize GaAs DH and InP wafer samples that had previously been characterized on an LED-based PLE. Similar data trends are observed while the Xe arc lamp system has nearly 6 times as many data points recorded for the same wavelength range. The GaAs DH exhibits evidence of surface degradation and the corresponding SRH lifetimes and recombination velocities can be quantified once coupled to Sentaurus simulations. The InP crystalline wafer further proves that the Xe arc lamp based PLE can be used to take more detailed measurements.
研究不足
The system can currently characterize materials with band gap energies corresponding to emissions of >850nm. Materials with emission peaks <850nm could easily be tested with a second dichroic mirror with a different cut-on wavelength.
1：Experimental Design and Method Selection:
The proposed PLE system utilizes a 300W Xe arc lamp as the excitation source, followed by collimation optics and a liquid crystal filter for removal of infrared radiation. Wavelength selection of the broadband source is achieved via a custom Ebert-Fastie monochromator with grating efficiencies of >70% for the entirety of the near UV to NIR spectrum.
2：Sample Selection and Data Sources:
A GaAs double heterostructure (DH) and an InP crystalline wafer were used as calibration standards.
3：List of Experimental Equipment and Materials:
300W Xe arc lamp, custom Ebert-Fastie monochromator, liquid crystal filter, higher order radiation blocking filters, 30% reflection / 70% transmission beamsplitter, custom dichroic mirror, photodiode, lock-in amplifier, power meter sensor.
4：Experimental Procedures and Operational Workflow:
The system employs optical chopping to reduce background noise and improve signal detection of the photodiode and power meter. The photodiode connects into a Stanford Research Lock-in Amplifier. The power meter sensor has a built-in neutral density filter and internally accounts for its spectral responsivity.
5：Data Analysis Methods:
The PLE signal is normalized to the maximum measured PLE signal.
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