“…Figure 6 b illustrates the Al 0.05 Ga 0.45 In 0.5 P/Al 0.4 Ga 0.1 In 0.5 P MQW LED structure for red for display (RD) with a room temperature peak wavelength of 630 nm. The detailed device structure has been discussed earlier 20 – 23 , 26 . The chip sizes are 800 × 1345 µm 2 for BL LED, 191 × 270 µm 2 for BD and GD LEDs, and 300 × 300 µm 2 for RD LED.…”
Section: Methodsmentioning
confidence: 99%
“…The optical and electrical studies were conducted with a varied range of temperatures 77–800 K using a cryostat. The detail of the LEDs and photodiodes measurements and studied are explained previously 20 – 23 , 26 . Figure 7 Images of LEDs.…”
The commercial InGaN-based (blue and green) and AlGaInP-based (red) multiple quantum well (MQW) lighting emitting diodes (LEDs) were studied in a wide range of temperatures up to 800 K for their light emission and detection (i.e., LEDs operated under reverse bias as photodiodes (PDs)) characteristics. The results indicate the feasibility of integrating a pair of selected LEDs to fabricate high temperature (HT) optocouplers, which can be utilized as galvanic isolation to replace the bulky isolation transforms in the high-density power modules. A detailed study on LEDs and PDs were performed. The external quantum efficiency (EQE) of the LED and PDs were calculated. Higher relative external quantum efficiency (EQE) and lower efficiency droops with temperatures are obtained from the blue and green LEDs for display compared with the blue one for lighting and red LED for display. The blue for lighting and red for display devices show superior responsivity, specific detectivity (D*), and EQE compared with blue and green for display when operated as PDs. The results suggest that red LED devices for display can be used to optimize HT optocouplers due to the highest wavelength overlapping compared with others.
“…Figure 6 b illustrates the Al 0.05 Ga 0.45 In 0.5 P/Al 0.4 Ga 0.1 In 0.5 P MQW LED structure for red for display (RD) with a room temperature peak wavelength of 630 nm. The detailed device structure has been discussed earlier 20 – 23 , 26 . The chip sizes are 800 × 1345 µm 2 for BL LED, 191 × 270 µm 2 for BD and GD LEDs, and 300 × 300 µm 2 for RD LED.…”
Section: Methodsmentioning
confidence: 99%
“…The optical and electrical studies were conducted with a varied range of temperatures 77–800 K using a cryostat. The detail of the LEDs and photodiodes measurements and studied are explained previously 20 – 23 , 26 . Figure 7 Images of LEDs.…”
The commercial InGaN-based (blue and green) and AlGaInP-based (red) multiple quantum well (MQW) lighting emitting diodes (LEDs) were studied in a wide range of temperatures up to 800 K for their light emission and detection (i.e., LEDs operated under reverse bias as photodiodes (PDs)) characteristics. The results indicate the feasibility of integrating a pair of selected LEDs to fabricate high temperature (HT) optocouplers, which can be utilized as galvanic isolation to replace the bulky isolation transforms in the high-density power modules. A detailed study on LEDs and PDs were performed. The external quantum efficiency (EQE) of the LED and PDs were calculated. Higher relative external quantum efficiency (EQE) and lower efficiency droops with temperatures are obtained from the blue and green LEDs for display compared with the blue one for lighting and red LED for display. The blue for lighting and red for display devices show superior responsivity, specific detectivity (D*), and EQE compared with blue and green for display when operated as PDs. The results suggest that red LED devices for display can be used to optimize HT optocouplers due to the highest wavelength overlapping compared with others.
“…A few studies on optoelectronic materials and devices for high-temperature applications were conducted and reported in recent years 16 – 21 . The spontaneous emission quantum efficiency (QE) of different light-emitting diode (LED) materials (i.e., indium-gallium-nitride-based (InGaN-based) multiple quantum wells (MQWs)) over a wide range of temperature was studied using photoluminescence (PL) measurements 17 .…”
Section: Introductionmentioning
confidence: 99%
“…These studies 17 – 20 prove that AlGaN-based and AlGaInP-based MQW structures can be utilized to form LED devices in high-temperature optoelectronic applications. In addition, the spectral responsivity (SR) of InGaN-based MQW structures was investigated with the temperature range of − 200 °C to 500 °C 21 . The results indicate that the photodiodes can be used in high-temperature optocouplers.…”
Section: Introductionmentioning
confidence: 99%
“…The design was focused on the investigation and optimization of driving capability and response speed. Commercial high-temperature LEDs, which were studied in previous work 17 – 21 , are used as emitters and detectors in the optocouplers to investigate their optical coupling behaviors. Low temperature co-fired ceramic (LTCC) was utilized for the packaging of the optical isolator.…”
This paper reports high-temperature optocouplers for signal galvanic isolation. Low temperature co-fired ceramic (LTCC) technology was used in the design and fabrication of the high-temperature optocoupler package. The optimal coupling behaviors, driving capabilities and response speed of the optocouplers were concentrated and investigated in this paper. Emitters and detectors with different emission and spectral wavelengths were studied to achieve optimal coupling behaviors. Relatively high coupling efficiency is achieved with emitters and detectors of emission and spectral wavelength in the red spectrum (i.e., 620–750 nm), leading to higher current transfer ratios (CTR). To further enhance the electrical performance, optocouplers with multiple detectors in parallel were designed and fabricated. CTR, leakage current and response speed (i.e., propagation delay, rise time and fall time) of the optocouplers were characterized over a range of temperatures from 25 to 250 °C. The CTR degrades at high temperatures, while the leakage current and response speed show little degradation with varying temperatures. Furthermore, the behaviors of the optocouplers with varying temperatures are modeled and analyzed.
Organic optoelectronic synaptic devices that can reliably operate in high‐temperature environments (i.e., beyond 121°C) or remain stable after high‐temperature treatments have significant potential in biomedical electronics and bionic robotic engineering. However, it is challenging to acquire this type of organic devices considering the thermal instability of conventional organic materials and the degradation of photoresponse mechanisms at high temperatures. Here, high‐temperature synaptic phototransistors (HTSPs) based on thermally stable semiconductor polymer blends as the photosensitive layer are developed, successfully simulating fundamental optical‐modulated synaptic characteristics at a wide operating temperature range from room temperature to 220°C. Robust optoelectronic performance can be observed in HTSPs even after experiencing 750 h of the double 85 testing due to the enhanced operational reliability. Using HTSPs, Morse‐code optical decoding scheme and the visual object recognition capability are also verified at elevated temperatures. Furthermore, flexible HTSPs are fabricated, demonstrating an ultralow power consumption of 12.3 aJ per synaptic event at a low operating voltage of −0.05 mV. Overall, the conundrum of achieving reliable optical‐modulated neuromorphic applications while balancing low power consumption can be effectively addressed. This research opens up a simple but effective avenue for the development of high‐temperature and energy‐efficient wearable optoelectronic devices in neuromorphic computing applications.
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