Ultraviolet light-emitting diodes (LEDs) suffer from a low wall-plug efficiency, which is to a large extent limited by the poor light extraction efficiency (LEE). A thin-film flip-chip (TFFC) design with a roughened N-polar AlGaN surface can substantially improve this. We here demonstrate an enabling technology to realize TFFC LEDs emitting in the UVB range (280-320 nm), which includes standard LED processing in combination with electrochemical etching to remove the substrate. The integration of the electrochemical etching is achieved by epitaxial sacrificial and etch block layers in combination with encapsulation of the LED. The LEE was enhanced by around 25% when the N-polar AlGaN side of the TFFC LEDs was chemically roughened, reaching an external quantum efficiency of 2.25%. By further optimizing the surface structure, our ray-tracing simulations predict a higher LEE from the TFFC LEDs than flip-chip LEDs and a resulting higher wall-plug efficiency.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9936579 | PMC |
| http://dx.doi.org/10.1021/acsphotonics.2c01352 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
To further enhance the performance of GaN-based thin-film flip-chip light-emitting diodes (TFFC-LEDs), we designed and fabricated two sets of high-power blue chips with conventional and reflective current-blocking layers (CBL) The conventional CBL is composed of SiO, whereas the reflective CBL consists of SiO and a distributed Bragg reflector (DBR). We systematically characterized their optoelectronic performance. The results indicate that at an injection current of 350 mA, the light output power (LOP) and external quantum efficiency (EQE) of the TFFC-LEDs with a reflective CBL increased by 4.
View Article and Find Full Text PDFIncreased Light Extraction of Thin-Film Flip-Chip UVB LEDs by Surface Texturing.
ACS Photonics
February 2023
Chalmers University of Technology, Department of Microtechnology and Nanoscience, 41296Gothenburg, Sweden.
Ultraviolet light-emitting diodes (LEDs) suffer from a low wall-plug efficiency, which is to a large extent limited by the poor light extraction efficiency (LEE). A thin-film flip-chip (TFFC) design with a roughened N-polar AlGaN surface can substantially improve this. We here demonstrate an enabling technology to realize TFFC LEDs emitting in the UVB range (280-320 nm), which includes standard LED processing in combination with electrochemical etching to remove the substrate.
View Article and Find Full Text PDFLight Extraction Analysis of AlGaInP Based Red and GaN Based Blue/Green Flip-Chip Micro-LEDs Using the Monte Carlo Ray Tracing Method.
Micromachines (Basel)
December 2019
Center for Photonics and Semiconductors, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China.
Micro-scale light emitting diodes (micro-LEDs) commonly employ a thin-film flip-chip (TFFC) structure whose substrate is lifted off by an excimer laser. However, flip-chip (FC) micro-LEDs with a substrate can provide a sharp rise on sidewall emission by increasing the sidewall area. Here, we investigate the influence of substrate thickness, encapsulation, surface texture, microstructures between the substrate and epilayer, as well as the size, cutting shape, and angle of the chip on the light extraction efficiencies (LEEs) of FC micro-LEDs by using the Monte Carlo ray tracing method.
View Article and Find Full Text PDFWe demonstrate a thin-film flip-chip (TFFC) process for LEDs grown on freestanding c-plane GaN substrates. LEDs are transferred from a bulk GaN substrate to a sapphire submount via a photoelectrochemical (PEC) undercut etch. This PEC liftoff method allows for substrate reuse and exposes the N-face of the LEDs for additional roughening.
View Article and Find Full Text PDFComprehensive studies were carried out to investigate the light extraction efficiency of thin-film flip-chip (TFFC) light-emitting diodes (LEDs) with anatase TiO(2) microsphere arrays by employing the finite-difference time-domain method. The quantum well position and the resonant cavity effect were studied to obtain optimum light extraction for the planar TFFC LED. Further enhancement in light extraction was achieved by depositing microsphere arrays on the TFFC LED.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!