Session Index

Various Al atomic contents were doped into HfGaO and were deposited on sapphire substrates at approximately 80 K by using a vapor cooling condensation system. By using energy-dispersive spectrometer measurements, it was found that the Al atomic content in the AlHfGaO films increased with an increase of the deposition temperature of an Al2O3-powder- loaded tungsten boat. AlHfGaO films with an Al atomic content of 3.16% had a higher optical bandgap energy (5.36 eV) than did undoped HfGaO films (5.14 eV). Increasing the Al atomic content reduced the Ga atomic content; however, the Hf atomic content was similarly unchanged, which revealed that the Al dopants substituted Ga atoms. By using X-ray photoelectron spectroscopy measurements, it indicated that the oxygen vacancy defects in HfGaO films were suppressed by doping with Al to produce AlHfGaO films. These results verified that the Al doping of HfGaO films could effectively modify the bandgap energy and could suppress oxygen vacancy defects.

The AlHfGaO films with various Al atomic contents were used as the channel layers of ultraviolet phototransistors. The undesired oxygen vacancy defects residing in the AlHfGaO films could be compensated and suppressed by doping Al dopants. In addition to modulate the cutoff wavelength of the ultraviolet phototransistors by doping various Al atomic contents in the AlHfGaO channel layers, the performances of the resulting phototransistors could be improved due to the reduction of the amount of oxygen vacancy defects. Compared with the phototransistors using the HfGaO channel layer, when the phototransistors using the AlHfGaO channel layer with an Al atomic content of 3.16%, its cutoff wavelength was shifted from 240 to 225 nm, and the detectivity was improved from 1.62 × 1012 to 3.16 × 1012 Jones. Besides, the photoresponse speed was also improved by increasing Al atomic content in the AlHfGaO channel layer of the phototransistors.

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we demonstrate a spectral-phase SPR imaging sensor. It probes the sensitive phase response at plasmonic resonance with stable spectral SPR image. In our design, surface plasmon excitation is placed inside a polarizer cavity with perpendicular polarization orientation. At resonance wavelengths, the phase related polarization orientation allows light to leave the polarizer cavity, which produces corresponding spectral profile at SPR image. In refractive index measurements, the sensor detected different concentrations of NaCl solutions and the sensor resolution was 8.4 x 10-6 RIU. The spectral-phase SPR imaging sensor can find potential applications in biosensing, chemical sensing and drug discovery.

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A Mach-Zehnder direction coupler with a 50:50 splitting ratio in a silicon platform
demonstrates frequency-modulated continuous wave (FMCW) characterizations in velocity and
distance through Hilbert transform resampling. The measurement speed is 200 mm/second with
a 0.2 mm/second standard deviation. The final most extended detection range can demonstrate
1052.5 cm distance with a standard deviation of 0.006 cm and a full width at half maximum
(FWHM) of 0.0043 cm using 1.25 mega-sample-rate data acquisition.

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This paper presents a fiber Bragg grating vibration sensor for tuning guitars to analyze the variations in non-stationary signals using fast Fourier transform (FFT) and continuous wavelet transform (CWT).

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