Fluorescence-enhanced Si photodiodes for ultraviolet C rays (UVC) measurements

Abstract

The ultraviolet C rays (UVC, wavelength λ = 100–280 nm) light generated by a Hg lamp ( λ = 254 nm) and UVC light-emitting diodes (LEDs, λ = 265 and 275 nm) was detected using a fluorescence-enhanced silicon photodiode (FE-PD). Ce-doped yttrium aluminum garnet (YAG:Ce), YAG:Pr, YAG:Eu, YAG:Tb, YAG:Cr, Al2O3:Ti, Al2O3:Cr, MgAl2O4:Ti, MgAl2O4:Cr, MgAl2O4:Mn, and commercial fluorescent acrylic resins were tested as phosphor sources to enhance the output signal intensity of the FE-PD irradiated with UVC light. The resulting output signal intensity increased linearly with the UVC light strength, which was adjusted by raising the input current of the UVC LEDs from 0 to 40 mA. The sensitivity of the fabricated UVC detectors, assessed based on the calibration curve slope, varied depending on the phosphor materials. The phosphors effectively enhanced the output signal intensity of the FE-PD, which was up to six times greater than that of the visible and near infrared Si-PD without phosphors; the stronger output signal intensity was achieved using YAG:Tb, YAG:Cr, and a red fluorescent acrylic resin. The visible light emitted by phosphors under UVC irradiation is useful for detecting UVC light by the eye when using FE-PD.

Effect of Surface Structure on the Sensitivity of Fluorescence-Enhanced Si Photodiodes for Ultraviolet C Light Measurement

“…To this end, fluorescence-enhanced photodiodes (FE-PD) have been developed using silicon photodiodes (Si-PD) and phosphors that transform UVC light into visible and/or near-infrared (NIR) light. 1 FE-PD can detect UVC light (λ = 254 nm, 265 nm, and 275 nm) with high sensitivity using FE-PD.…”

Red Photoluminescence from Fe-Doped MgAl2O4 Crystals

“…A fluorescence-enhanced photodiode (FE-PD), which converts ultraviolet-C (UVC) light into red or near-infrared (NIR) light via phosphors, is reported as a sensitive UVC sensor. 1 Phosphors emitting red or NIR lights have been effectively detected via Si photodiodes (Si PD), which are sensitive to lights with long wavelengths spanning from red to NIR. Notably, phosphors such as Eu-doped Y 3 Al 5 O 12 (YAG), Cr-doped Al 2 O 3 , Cr-doped YAG, and Cr-doped MgAl 2 O 4 (spinel) emitting red color PL have been identified as suitable candidates for FE-PD applications.…”

“…Notably, phosphors such as Eu-doped Y 3 Al 5 O 12 (YAG), Cr-doped Al 2 O 3 , Cr-doped YAG, and Cr-doped MgAl 2 O 4 (spinel) emitting red color PL have been identified as suitable candidates for FE-PD applications. 1 The red photoluminescence (PL) emitted by Fe-doped MgAl 2 O 4 2-4…”

“…Phase-diagrams at both regions are listed together by Levin et al 7 While MgAl 2 O 4 crystals are excellent substrates for impurity-doped phosphors, challenges persist concerning their composition, electric charges of impurities, and crystal sites. [1][2][3][4][8][9][10][11][12][13][14][15][16][17][18][19][20] Many studies have delved into the properties of phosphors, such as Cr-doped MgAl 2 O 4 , [9][10][11][12] Ti-doped MgAl 2 O 4 , [13][14][15][16] and Mn-doped MgAl 2 O 4 . [17][18][19][20] However, few reports exist on crystal growth and comprehensive assessment of PL from Fe-doped MgAl 2 O 4 .…”

“…PL images from the crystals were observed using an L-835 color Si CMOS camera and L600-12 lens (Hozan, Co., Japan) coupled with a long-pass filter (with a cut-off wavelength at λ = 550 nm). 1,[18][19][20] X-ray powder diffraction patterns from the grown spinel were measured using RINT ULTIMA (Rigaku Co., Japan). The PL peak intensity at λ = 730 nm from 0.05 mol%-2.0 mol% Fe 2 O 3 -doped crystals grown in 100 vol% O 2 (Fig.…”