研究目的
Investigating the performance of a long wavelength type-II InAs/GaSb superlattice photodetector using a resonant tunneling diode structure.
研究成果
The demonstrated RTD LW photodetector using T2SL materials covers the long wavelength range with a response maximum at 7.5 μm and a 50% cutoff wavelength at 9.6 μm at 77 K. The device achieves an unusual quantum efficiency of 147% and a responsivity of 8.9 A/W at 1.45 V, attributed to the large gain under resonant tunneling conditions. The shot noise limited detectivity D* is 1.2×1010cm · Hz/W at 1.45 V at 77 K.
研究不足
The study is limited to the performance evaluation at 77 K, and the operational temperature range where negative differential resistance phenomena are observed is up to 160 K. The photodetector's performance at higher temperatures is not explored.
1：Experimental Design and Method Selection:
The study involves the design and fabrication of a resonant tunneling diode (RTD) photodetector using type-II InAs/GaSb superlattice materials. The methodology includes molecular beam epitaxy for sample growth and photolithography for device fabrication.
2：Sample Selection and Data Sources:
The sample is grown on a semi-insulating GaSb (001) substrate. The structural quality is assessed using high-resolution x-ray diffraction.
3：List of Experimental Equipment and Materials:
Molecular beam epitaxy system, photolithography equipment, wet chemical etching setup, and Fourier transform infrared spectrometer for photocurrent spectra measurement.
4：Experimental Procedures and Operational Workflow:
The sample is processed into a circular mesa structure, and Ti/Au is used for Ohmic contacts. The photoresponse is measured at different bias voltages and temperatures.
5：Data Analysis Methods:
The responsivity and quantum efficiency are calculated from the photocurrent spectra. The shot noise limited detectivity is derived from the responsivity and dark current measurements.
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