IR Light-emitting Diodes Research Articles

Light-emitting AlGaAs/GaAs diodes based on ingaas strain-compensated quantum wells with minimized internal losses OF 940 nm radiation absorption

IR light-emitting diodes based on InGaAs/AlGaAs multiple quantum wells and AlxGa1–xAsyP1–y-layers that compensate stresses in the active region have been developed. The optical losses caused by absorption of radiation generated by the active region (λ = 940 nm) were studied at different doping levels of n-GaAs substrates. It has been shown that reducing the donor doping level from 4 × 1018 to 5 × × 1017 cm–3 gives an increase in the quantum efficiency of LEDs by ~ 30%. A technology that eliminates optical losses caused by absorption during radiation output has been developed. By removing the growth substrate and transferring the device structure to a carrier substrate with the formation of a rear metal reflector, LEDs were created that demonstrate a twofold increase in external quantum efficiency and efficiency (~ 40%) compared to the technology of outputting radiation through an n-GaAs substrate.

Investigation of Power IR (850 nm) Light-Emitting Diodes Manufacturing by Lift-Off Technique of AlGaAs–GaAs-Heterostructure to Carrier-Substrate

Investigation of Power IR (850 nm) Light-Emitting Diodes Manufacturing by Lift-Off Technique of AlGaAs–GaAs-Heterostructure to Carrier-Substrate

Application of Performance Test Method in Korea for LED Optical Medical Device Samples

This study obtained key performance items related to phototherapy and the standards of light-emitting diode (LED) phototherapy devices through the published literature to secure LED phototherapy device safety in South Korea. Based on these items and IEC 62471-1 for the photobiological safety of lamps and lamp systems, a performance test method and wavelength parameters, which are the main performance indicators of the LED phototherapy device, were derived. We conducted a performance test derived from this study using samples with the same performance as the sample that is being developed. The samples comprised a laser and IR LED, red LED, and blue LED. All samples were within ±5%, of the standard threshold. The 455 nm blue LED and 625 nm red LED were close to the set value with a difference of 1 to 2 nm; their wavelengths’ accuracy was within ±0.32%, ±0%, and ±0.219%, depending on the samples’ wavelengths, which was the same or similar to the error range of ±0%. As for laser and IR LED, the difference from the set value was as large as 2 to 7 nm, and their error ranges were close to ±1%, as shown by ±0.615%, ±0.828%, or ±0.591%, which were larger than the values for red and blue LEDs.

Investigation of power IR (850 nm) light-emitting diodes manufacturing by lift-off technique of AlGaAs-GaAs- heterostructure to carrier-substrate

Development of lift-off technique of AlGaAs/GaAs- heterostructures, grown by the Metalorganic vapour-phase epitaxy, to GaAs carrier-substrate using silver-containing paste or Au-In compound has been carried out. Forming process of frontal ohmic contact to GaAs n-type conductivity based on contact systems Au(Ge)/Ni/Au and Pd/Ge/Au with specific contact resistance (2-5)·10-6 Ω·cm2 has been investigated. Analyzed was the influence of heterostructure lift-off technique and forming process of frontal ohmic contact on the IR light-emitting diodes parameters: minimum light-emitting diodes (1 mm2 square) series resistance was 0.16 Ω. Optical power 270 mW at current 1.5 A has been achieved. Keywords: AlGaAs/GaAs- heterostructure, light-emitting diode, transfer to carrier-substrate, Au--In- compound, ohmic contacts.

Исследование технологии изготовления мощных ИК (850 nm) светодиодов, получаемых методом переноса AlGaAs-GaAs-гетероструктуры на подложку-носитель

Development of lift-off technique of AlGaAs/GaAs heterostructures, grown by the MOCVD technique, to GaAs carrier-substrate using silver-containing paste or Au-In compound has been carried out. Forming process of frontal ohmic contact to GaAs n-type conductivity based on contact systems Au(Ge)/Ni/Au and Pd/Ge/Au with specific contact resistivity 2-5·10-6 Ом·см2 has been investigated. Analyzed was the influence of heterostructure lift-off technique and forming process of frontal ohmic contact on the IR light-emitting diodes parameters: minimum light-emitting diodes (1mm2 square) series resistance was 0.16 Ohm. Optical power 270 mW at current 1.5A has been achieved.

MAMDANI-TYPE FUZZY CONTROLLER TO DETERMINE BLOOD PRESSURE LEVELS BY REFLECTION PPG

This document presents the design of a fuzzy control system applying photoplethysmography techniques to generate input data and Mamdani-type fuzzy logic for its processing and generation of system output values, through which blood pressure levels can be indicated based on the parameters recommended by the medical area for an adult person. The integral design of the system includes the acquisition of the input signals, obtained through the reflection photoplethysmography technique, by means the optical coupling between IR light-emitting diodes and photo receptors, which allow the flow of current proportional to the amount of reflected light by blood, which is related to the flow level of the cardiac cavities, derived from the systolic and diastolic stages of the cardiac cycle. The fuzzy control was designed with two inputs and one output of 5 triangular membership functions each using the hardware description language (VHDL), the fuzzification, inference, aggregation and defuzzification stages were designed using the COSAA method. The response values ​​obtained using the Test Bench tool of ISE Design suite were compared with theoretical values ​​and with values ​​obtained with the Fuzzy Logic Designer tool of Matlab, the results showed an excellent approximation.

Midwavelength Infrared Colloidal Nanowire Laser.

Realizing bright colloidal infrared emitters in the midwavelength infrared (or mid-IR), which can be used for low-power IR light-emitting diodes (LEDs), sensors, and deep-tissue imaging, has been a challenge for the last few decades. Here, we present colloidal tellurium nanowires with strong emission intensity at room temperature and even lasing at 3.6 μm (ω) under cryotemperature. Furthermore, the second-harmonic field at 1.8 μm (2ω) and the third-harmonic field at 1.2 μm (3ω) are successfully generated thanks to the intrinsic property of the tellurium nanowire. These unique optical features have never been reported for colloidal tellurium nanocrystals. With the colloidal midwavelength infrared (MWIR) Te nanowire laser, we demonstrate its potential in biomedical applications. MWIR lasing has been clearly observed from nanowires embedded in a human neuroblastoma cell, which could further realize deep-tissue imaging and thermotherapy in the near future.

High efficiency (EQE=37.5%) infrared (850 nm) light-emitting diodes with Bragg and mirror reflectors

Developed and investigated are IR (850 nm) light-emitting diodes based on AlGaAs/Ga(In)As heterostructures grown by the MOCVD technique with multiple quantum wells in the active region and with a double optical reflector consisted of a multilayer Al0.9Ga0.1As/Al0.1Ga0.9As Bragg heterostructure and an Ag mirror layer. Light-emitting diodes with the external quantum efficiency EQE=37.5% at current densities greater than >10 A/cm2 have been fabricated. Keywords: IR light-emitting diode, AlGaAs/GaAs heterostructure, Bragg reflector, InGaAs quantum wells.

Investigation of methods for texturing light-emitting diodes based on AlGaAs/GaAs heterostructures

Investigations of methods for texturing the light-emitting surface of IR light-emitting diodes (LEDs) (wavelength 850 nm) based on AlGaAs/GaAs heterostructures with Bragg reflectors have been carried out. Developed were methods of liquid and plasma-chemical etching of solid solution for creating peaks (pyramids) of different form, 0.2-1.5 μm height. Estimation of the effect of texturing methods and also configuration of peaks on the light-emitting diode electroluminescence intensity has been performed. The increase of the electroluminescence intensity by 25% has been achieved. Keywords: light-emitting diode, texturing, etching methods, electroluminescence.

Влияние внутренних отражателей на эффективность инфракрасных (850 нм) светодиодов

Investigated are IR light-emitting diodes with 850 nm radiation wavelength, based on AlGaAs/GaAs heterostructures grown by the method of MOC-hydride epitaxy with a Bragg reflector and additional “reflecting” layer Al0.9Ga0.1As, which ensures the decrease of optical losses of the generated radiation. Developed is the post growth technology for forming frontal ohmic contacts and for texturing the light-emitting surface, which ensures the decrease of ohmic losses and the increase of the radiation extraction efficiency from a crystal. External quantum efficiency of light-emitting diodes with two internal reflectors and surface texturing exceeded 9% at the current range 0.1-1.4A

Высокоэффективные (EQE=37.5%) инфракрасные (850 нм) светодиоды с брэгговским и зеркальным отражателями

Developed and investigated are IR (850nm) light-emitting diodes based on AlGaAs/Ga(In)As heterostructures grown by the MOC-hydride epitaxy technique with multiple quantum wells in the active region and with a double optical reflector consisted of a multilayer Al0.9Ga0.1As/Al0.1Ga0.9As Bragg heterostructure and an Ag mirror layer. Light-emitting diodes with the external quantum efficiency (EQE) of 37.5% at current densities greater than 10A/cm2 have been fabricated.

Photovoltaic Characteristics of LEDs with Two in-Series p–n Junctions

Photovoltaic characteristics of high-power IR light-emitting diodes (LEDs) manufactured by OSRAM GmbH on the basis of structures with two in-series p–n junctions have been studied. The spectral range of operation of photovoltaic converters based on LEDs with different emission wavelengths was determined. It was shown that the efficiency of photovoltaic conversion of these LEDs reaches values exceeding 30% at a wavelength of 808 nm. The high (up to 2.6 V) output voltage of these converters allows them to be used for direct feeding of low-power electronic devices by optical radiation.

Исследование методов текстурирования светодиодов на основе гетероструктур AlGaAs/GaAs

Investigations of methods for texturing the light-emitting surface of IR light-emitting diodes (LEDs) (wavelength 850 nm) based on AlGaAs/GaAs heterostructures with Bragg reflectors have been carried out. Developed were methods of liquid and plasma-chemical etching of solid solution for creating peaks (pyramids) of different form, 0.2–1.5 µm height. Estimation of the effect of texturing methods and also configuration of peaks on the light-emitting diode electroluminescence intensity has been performed. The increase of the electroluminescence intensity by 25% has been achieved.

745 Low-level red and infrared lights provide anti-aging skin benefits

Photobiomodulation (PBM), also known as low-level light therapy, uses photons at a non-thermal irradiance to alter biological activities, such as reducing pain and inflammation, augmenting tissue repair and promoting regeneration, and skin rejuvenation. PBM can have either inhibitory or stimulatory effects on various biological activities at the same wavelength with either higher or lower energy densities. This study's objective is to evaluate the anti-aging benefits provided by non-coherent light-emitting diodes (LEDs). Human dermal fibroblasts or human skin explant tissues were treated by red (640 nm) and/or infrared (IR, 830 nm) LED lights at 0.3 J/cm2 (0.5 mW/cm2 for 10 minutes) to examine the antiaging benefits of PBM by light. Reactive oxygen species (ROS) were measured using a fluorescent reactive dye, real time qPCR was used to investigate gene expression, and ELISA/histology/non-invasive fluorescent measurement were used to assess protein production. Red and IR lights at 0.3 J/cm2 didn’t induce ROS formation in human fibroblasts. Red and/or IR LED lights could enhance elastin (ELN) gene expression and elastin production in human fibroblasts as well as induce COL1A1, COL3A1, and ELN genes expression and increase procollagen and elastin fibers formation in human skin explants. Furthermore, red and IR Iights could significantly induce hyaluronic acid (HA) production in human fibroblasts obtained from both Caucasian and African American donors. In conclusion, low-level red and/or IR LED lights stimulated the production of multiple biomarkers with proven anti-aging skin benefits. Taken together, low-level red and/or infrared LED lights provide a convenient, safe and effective mode of anti-aging treatment for photo-damaged skin.

The exploration of monochromatic near-infrared LED improved anoxygenic photosynthetic bacteria Rhodopseudomonas sp. for wastewater treatment

The future wastewater treatment requires high-efficiency and energy-saving technology. Anoxygenic photosynthetic bacteria (APB) is deemed as an eco-friendly microorganism, which could be employed in wastewater treatment. Here, monochromatic near-infrared (MNIR) light emitting diode (LED) was used, and three key factors (light quality, light intensity and photoperiod) of it were analyzed by a response surface methodology (RSM) in APB wastewater treatment. The results showed that light quality was the biggest impact factor in APB wastewater treatment, and nearly 58.07% of NH4+-N and 70.62% of chemical oxygen demand (COD) could be removed based on 46.4% of that theoretically possible. The light quality’s study revealed that APB had the highest NH4+-N and COD removal, biomass production, and bacteriochlorophyll a production with 850nm IR LED. Moreover, the application of optimal MNIR LED could not only save energy, but also avoid algae bloom of photo-bioreactors (PBR).

Measurement of the water content in oil and oil products using IR light-emitting diode–photodiode optrons

The feasibility of using light-emitting devices, the radiation spectrum of which has maxima at wavelengths of 1.7, 1.9, and 2.2 μm for determining the water concentration in oil and oil products (gasoline, kerosene, diesel fuel) has been demonstrated. It has been found that the measurement error can be lowered if (i) the temperature of the light-emitting diode is maintained accurate to 0.5–1.0°C, (ii) by using a cell through which a permanently stirred analyte is pumped, and (iii) by selecting the repetition rate of radiation pulses from the light-emitting diodes according to the averaging time. A meter of water content in oil and oil products has been developed that is built around IR light-emitting device–photodiode optrons. This device provides water content on-line monitoring accurate to 1.5%.

Spectral Responses of Light‐Emitting Diodes as a Photodiode and Their Applications in Optical Measurements

Spectral responses of four light‐emitting diodes (LEDs) were investigated because their uses as a photodiode are growing these days. An LED showed reasonable sensitivity to shorter wavelengths which the LED emits. Their spectral response ranges are same or relatively wider than their emission range. In addition, LEDs were used as detectors to analyze test dyes with absorbance measurement technique or with fluorescence measurement technique. Absolute noise level of 0.0001 absorbance unit was observed with the blue LED (nominal λmax = 455 nm) photodiode. Phosphate amount in Kumho River (located in Gyeongsan, South Korea) was determined using IR LED (nominal λmax = 805 nm) as a photosensor. A green LED (nominal λmax = 520 nm) was used to excite rhodamine B (excitation λmax = 560 nm, emission λmax = 575 nm) and red LEDs (nominal λmax = 660 nm) were used to detect fluorescence light emitted from the fluorescence dye. The LOD of rhodamine B was found to be 26 nM with four red LEDs as a photodiode and without using optical filters.

Phototactic behavior 10: phototactic behavioral effects ofPlodia interpunctella(Hübner) (Lepidoptera: Pyralidae) adults to different light-emitting diodes of seven wavelengths

Phototactic behavioral responses of the Indian meal moth, Plodia interpunctella (), adults were determined to different light-emitting diodes (LEDs) of seven wavelengths, and their behavioral responses were compared to that using a commercial luring lamp (BLB) under laboratory conditions. Based on the attractive responses under optimal light conditions (60 lx luminance intensity and 30 min light exposure time), the green LED () showed the highest attractive rate (, 52.2 %), followed by the blue LED (, 33.9 %), the yellow LED (, 32.2 %), BLB (28.9 %), UV LED (365 nm, 22.8 %), the red LED (, 14.5 %), the white LED (450-620 nm, 10.6 %), and IR LED (730 nm, 9.5 %). In addition, the green LED to P. interpunctella adults was approximately 1.81 times more attractive than BLB. These results indicate that the green LED could be most useful for monitoring of P. interpunctella adults.

Wavelength-tunable infrared light emitting diode based on ordered ZnO nanowire/Si1–x Ge x alloy heterojunction

A novel infrared light emitting diode (LED) based on an ordered p-n heterojunction built of a p-Si1–xGex alloy and n-ZnO nanowires has been developed. The electroluminescence (EL) emission of this LED is in the infrared range, which is dominated by the band gap of Si1–xGex alloy. The EL wavelength variation of the LED shows a red shift, which increases with increasing mole fraction of Ge. With Ge mole fractions of 0.18, 0.23 and 0.29, the average EL wavelengths are around 1,144, 1,162 and 1,185 nm, respectively. The observed magnitudes of the red shifts are consistent with theoretical calculations. Therefore, by modulating the mole fraction of Ge in the Si1–xGex alloy, we can adjust the band gap of the SiGe film and tune the emission wavelength of the fabricated LED. Such an IR LED device may have great potential applications in optical communication, environmental monitoring and biological and medical analyses.

Phototactic behavior 4: Attractive effects of Trialeurodes vaporariorum adults to light-emitting diodes under laboratory conditions

The phototactic action of the greenhouse whitefly, Trialeurodes vaporariorum (Hemiptera: Aleyrodidae), adults to light-emitting diodes (LEDs) at various luminous intensities and light exposure times was investigated in a Y-maze bioassay chamber, and was compared with a standard luring lamp, which is used in commercial electric traps. Blue LED (97.3%) exhibited the highest potential attraction rate, followed by green LED (96.6%), white LED (93.7%), red LED (93.0%), UV LED (90.3%), yellow LED (89.3%), and IR LED (7.7%). Based on the relative efficiency values, the blue LED was approximately 1.2 times more effective than the luring lamp (84.3%). These results suggest that the blue LED was the most useful for monitoring of T. vaporariorum adults under optimal conditions.