Strategically constructed AlGaN doping barriers for efficient deep ultraviolet light-emitting diodes: erratum.

We present an erratum to our Letter [Opt. Lett.49, 2049 (2024)10.1364/OL.522212]. There is a careless omission of some references because our Letter is longer than the maximum allowed four pages. The missing references and their specific quote location are listed in the following. These corrections do not affect the data plotted in figures, discussion, or conclusion of the original Letter.

Strategically constructed AlGaN doping barriers for efficient deep ultraviolet light-emitting diodes.

Here, we propose a sandwich-like Si-doping scheme (undoped/Si-doped/undoped) in Al0.6Ga0.4N quantum barriers (QBs) to simultaneously promote the optoelectronic performances and reliability of deep ultraviolet light-emitting diodes (DUV-LEDs). Through experimental and numerical analyses, in the case of DUV-LEDs with conventional uniform Si-doping QB structure, severe operation-induced reliability degradation, including the increase of reverse leakage current (IR) and reduction of light output power (LOP), will offset the enhancement of optoelectronic performances as the Si-doping levels increase to an extent, which hinders further development of DUV-LEDs. According to a transmission electron microscope characterization and a numerical simulation, an improved interfacial quality in multiple quantum wells (MQWs) and more uniform carrier distribution within MQWs are demonstrated for our proposed Si-doping structure in comparison to the uniform Si-doping structure. Consequently, the proposed DUV-LED shows superior wall-plug efficiency (4%), IR at -6 V reduced by almost one order of magnitude, and slower LOP degradation after 168-h 100 mA-current-stress operation. This feasible doping scheme provides a promising strategy for the high-efficiency and cost-competitive DUV-LEDs.

Contact Engineering of III-Nitrides and Metal Schemes toward Efficient Deep-Ultraviolet Light-Emitting Diodes.

Throughout the development of III-nitride electronic and optoelectronic devices, electrically interfacing III-nitride semiconductors and metal schemes has been a long-standing issue that determines the contact resistance and operation voltage, which are tightly associated with the device performance and stability. Compared to the main research focus of the crystal quality of III-nitride semiconductors, the equally important contact interface between III-nitrides and metal schemes has received relatively less attention. Here, we demonstrate a comprehensive contact engineering strategy to realize low resistance to Al-rich n-AlGaN via pretreatment and metal scheme optimization. Prior to the metal deposition, the introduction of CHF3 treatment is conducive to the substantial resistance reduction, with the effect becoming more distinct by prolonging the treatment time. Furthermore, we compare different metal schemes, namely, Ti/Al/Ti/Au, Ti/Al/Ti/Pt/Au, and Cr/Ti/Al/Ti/Pt/Au, to form electrical contact on n-AlGaN. From microscale analysis based on multiple characterization methods, we reveal the correlation between electrical properties and the nature of the contact interface, attributing the contact improvement to the low-resistance Pt- and Cr-related alloy formation. Under the circumstance that no efforts have been devoted to optimizing the epitaxial growth, engineering the metal-semiconductor contact properties alone leads to a resistance value of 8.96 × 10-5 Ω·cm2. As a result, the fabricated deep-ultraviolet LEDs exhibit an ultralow forward voltage of 5.47 V at 30 A/cm2 and a 33% increase in the peak wall-plug efficiency.

Improved efficiency of AlGaN-based flip-chip deep-ultraviolet LEDs using a Ni/Rh/Ni/Au p-type electrode.

Here, we propose a thermally stable and high-reflectivity Ni/Rh/Ni/Au p-type electrode for AlGaN-based deep-ultraviolet (DUV) flip-chip light-emitting diodes (FCLEDs). We discover that the reflectance of Ni/Au electrode deteriorated significantly after rapid thermal annealing. Experiments show that Ni and Au agglomerate at high temperatures, and more incident photons traverse the gaps between the agglomerates, leading to a decrease in reflectance of Ni/Au after annealing. In contrast, the proposed Ni/Rh/Ni/Au p-type electrode shows remarkable thermal stability as a result of the suppression of Ni agglomeration by the Rh layer at high temperatures. Besides, due to the higher reflectivity of the Ni/Rh/Ni/Au electrode and its lower specific contact resistivity formed with p-GaN, the external quantum efficiency and wall-plug efficiency of a DUV FCLED with Ni/Rh/Ni/Au electrode are increased by 13.94% and 17.30% in comparison with the one with Ni/Au electrode at an injection current of 100 mA. The Ni/Rh/Ni/Au electrode effectively solves the long-standing dilemma of efficiency degradation of DUV FCLEDs with a Ni/Au electrode after high-temperature annealing.

Enhanced performance of 275-nm AlGaN-based deep-ultraviolet LEDs via internal-roughed sapphire and SiO2-antireflection film.

The internal-roughed sapphire in a 275-nm AlGaN-based deep-ultraviolet (DUV) LED is fabricated using a laser stealth dicing technique to improve the high-angle extraction. Furthermore, the low-angle extraction is enhanced by depositing a SiO2-antireflection film on the internal-roughed sapphire surface. Compared with conventional DUV LEDs with a light output power (LOP) of 33.05 mW at 350 mA, the LOP of DUV LEDs with internal-roughed sapphire and SiO2-antireflection film increases by 20.85% to 39.94 mW. In addition, combined with finite-difference time-domain simulations, the effect of internal-roughed sapphire on the transmission and light extraction efficiency (LEE) of the DUV LEDs is revealed. The combination of the internal-roughed sapphire substrate and SiO2-antireflection film improves the LEEs of transverse electric (TE) and transverse magnetic (TM) polarized light by 1.6% and 108%, respectively. These results offer the potential for large-scale, low-cost industrial production of high-efficiency DUV LEDs.

Unexpectedly Simultaneous Increase in Wavelength and Output Power of Yellow LEDs Based on Staggered Quantum Wells by TMIn Flux Modulation.

Pursuing efficient long-wavelength InGaN LED has been a troublesome issue to be solved, which forms interesting subjects for fundamental research, but finds also motivation in extensive applications. Here, we investigate the effect of TMIn (trimethylindium) flux variation for growing bandgap-engineered staggered quantum wells (QWs) on corresponding LED properties and demonstrate the unexpectedly simultaneous increase in light output power (LOP) and emission wavelength. At 20 mA, LEDs based on staggered QWs grown under low flux show an increase of 28% in LOP and longer wavelength compared to that under high flux. The experimental results reveal that TMIn flux affects crystalline quality and indium composition of epilayers. Under high TMIn flux, high in-plane strain exists between adjacent layers, accompanied by the composition pulling effect, which reduces indium incorporation for the following staggered QW growth and hinders realization of yellow light emission. According to simulation results, low-flux-grown staggered QWs contribute to increased carrier wavefunction overlap as well as enhanced electric field. Notably, the former enables high LOP, while the latter results in emissions towards long wavelength, promising to solve an ever-present concern that LED performance deteriorates with increasing emission wavelength. Therefore, this work shows great significance in thoroughly understanding growth conditions for bandgap-engineered staggered QW structures, which offers a facile solution to achieve efficient long-wavelength optoelectronics devices.

Strong Metal Phosphide-Phosphate Support Interaction for Enhanced Non-Noble Metal Catalysis.

Strong metal-support interaction (SMSI) is crucial for supported catalysts in heterogeneous catalysis. Here is the first report on strong metal phosphide-phosphate support interaction (SMPSI). The key to SMPSI is the activation of P species on the support, which leads to simultaneous generation of metal phosphide nanoparticles (NPs) and core-shell nanostructures formed by support migration onto the NPs. The encapsulation state of metal phosphide and charge transfer are identical to those of classical SMSIs and can be optimally regulated. Furthermore, the strong interactions of Co2 PL /MnP-3 not only significantly enhance the anti-oxidation and anti-acid capability of non-noble metal but also exhibit excellent catalytic activity and stability toward hydrogenating a wide range of compounds into value-added fine chemicals with 100% selectivity, which is even better than Pd/C and Pt/C. The SMPSI construction can be generally extended to other systems such as Ni2 PL /Mn3 (PO4 )2 , Co2 PL /LaPO4 , and CoPL /CePO4 . This study provides a new approach for the rational design of advanced non-noble metal catalysts and introduce a novel paradigm for the strong interaction between NPs and support.