A5067876798- GaN-based semiconductor devices and materials
- Semiconductor materials and devices
- Semiconductor Quantum Structures and Devices
- Ga2O3 and related materials
- ZnO doping and properties
- Spectroscopy and Laser Applications
- Advanced Fiber Laser Technologies
- Thin-Film Transistor Technologies
- Semiconductor Lasers and Optical Devices
- Acoustic Wave Resonator Technologies
Technische Universität Berlin
2023-2024
University of Padua
2024
Ferdinand-Braun-Institut
2023
Georgi Nadjakov Institute of Solid State Physics
2023
The long-term stability of ultraviolet (UV)-C light-emitting diodes (LEDs) is major importance for many applications. To improve the understanding in this field, we analyzed degradation AlGaN-based UVC LEDs and modeled variation electrical characteristics by 2D simulations based on results deep-level optical spectroscopy (DLOS). increase forward leakage current observed during ageing was ascribed an trap-assisted tunneling. analysis kinetics suggests role a defect diffusion process, possibly...
In this paper we investigate the reliability of AlGaN-based UV-C LEDs with an emission wavelength 265 nm. By submitting devices to constant current stress, two main electrical degradation processes are identified: a turn-on voltage shift and increase in forward leakage current. particular, these were respectively attributed to: (i) partial passivation Mg-doping concentration region adjacent contact, probably caused by local hydrogen diffusion, ii) diffusion/generation process defects...
We investigate the impact of Mg-doping on performance and degradation kinetics AlGaN-based UV-C light-emitting diodes (LEDs). By comparing LEDs from three wafers with different nominal doping levels [Mg/(Al+Ga) ratio: 0.15%, 0.5%, 1% in gas phase during epitaxy] AlGaN:Mg electron-blocking layer (EBL), we demonstrate following results: (i) A higher EBL results a optical power at low current levels, which is ascribed to an increased hole injection efficiency. (ii) The reduction follows...
The lifetime of deep-ultraviolet light-emitting diodes (LEDs) is still limited by a number factors, which are mainly related to semiconductor defects, and need be clarified. This paper improves the understanding UV LED degradation, presenting an analysis based on combined deep-level transient spectroscopy (C-DLTS), electro-optical characterization, simulations, carried out before during constant current stress test. original results this (i) C-DLTS measurements allowed us identify three...
Simulations of optical gain in aluminum gallium nitride (AlGaN) quantum wells are extended to the high charge carrier density regime required for achieving at 275 nm UV laser diodes. Coulomb interaction is modeled using 2nd Born approximation. We demonstrate good agreement with experimental data obtained through pumping, and predict spectra electrical pumping. Special consideration given contribution higher bands wide wells.
Herein, the lasing threshold and gain characteristics of ultraviolet‐C optically pumped edge‐emitting lasers with thick single‐quantum‐well (SQW) active regions are investigated by variable‐stripe length method. Positive net modal is observed in AlGaN‐based SQWs thicknesses up to 12 nm. The show a reduction power density increasing SQW thickness, lowest 1.3 MW cm −2 achieved for 9 nm laser. high low quantum wells attributed from excited states, where polarization fields screened carriers...
Abstract We studied four AlGaN-based 265 nm LEDs with increasing QW thickness (1.4, 3, 6 and 9 nm) during a constant current stress at 100 A cm −2 . focused our attention on the parasitic components of emission spectra low levels optical power recovery observed high levels. associated every peak or band to region in device where they can be generated, also demonstrating if are related band-to-band radiative through defects. At levels, we showed simultaneous effect decrease injection...
The market of Ultraviolet (UV) Light Emitting Diodes (LEDs) is expected to expand substantially in the coming years, thanks disinfection properties UV light; however, a detailed study on reliability-limiting processes fundamental step, for an effective deployment this technology. We investigated degradation mechanisms AlGaN-based Single Quantum Well (SQW) LEDs, with nominal emission wavelength 265 nm, area 0.1 mm<sup>2</sup> and current density 100 A·cm<sup>-2</sup>. By means constant stress...
Simulations of optical gain in aluminum gallium nitride (AlGaN) quantum wells are extended to the high charge density regime required for achieving at 275 nm UV laser diodes. Coulomb interaction is modeled using 2nd Born approximation. We demonstrate good agreement with experimental data obtained through pumping, and predict spectra electrical pumping.
In this paper, we investigated the degradation mechanisms that negatively affect reliability of UV-C LEDs. particular, modeled process involves trap generation identified through experimental electrical characteristics and contact by means numerical TCAD simulations.