Drive High Power UVC‐LED Wafer into Low‐Cost 4‐Inch Era: Effect of Strain Modulation

Abstract

Ultraviolet-C light-emitting diodes (UVC-LEDs) have great application in pathogen inactivation under various kinds of situations, especially in the fight against COVID-19. Unfortunately, its epitaxial wafers are so far limited to a size of 2 inches, which greatly increases the cost of massive production. In this work, a 4-inch crack-free high-power UVC-LED wafer is reported. This achievement relies on a proposed strain-tailored strategy, where a 3D to 2D (3D-2D) transition layer is introduced during the homo-epitaxy of AlN on the high temperature annealed (HTA)-AlN template, which successfully drives the original compressive strain into a tensile one and thus solves the challenge of realizing a high-quality Al 0.6 Ga 0.4 N layer with a flat surface. This smooth Al 0.6 Ga 0.4 N layer is nearly pseudomorphically grown on the strain-tailored HTA-AlN template, leading to 4-inch UVC-LED wafers with outstanding performances. The strategy succeeds in compromising the bottlenecked contradictory in producing a large-sized UVC-LED wafer on pronounced crystalline AlN template: The compressive strain in HTA-AlN allows for a crack-free 4-inch wafer, but at the same time leads to a deterioration of the AlGaN morphology and crystal quality. The launch of 4-inch wafers makes the chip fabrication process of UVC-LEDs match the mature blue one, and will definitely speed up the universal application of UVC-LED in daily life.

A Comprehensive Study of Defects in Gallium Oxide by Density Functional Theory

“…Raman spectra as shown in Figure 7 are acquired using a Horiba Raman spectroscope with a 638 nm red laser excitation passing through a 50x objective lens in backscattered mode with a spectral resolution of 0.5 cm −1 . The Raman spectra of the β-Ga2O3 samples exhibit the Raman phonon modes at 105.95 (𝐴 𝑔 (1) ), 118.76 (𝐵 𝑔 (1) ), 142.75 (𝐵 𝑔 (2) ), 175.63 (𝐴 𝑔 (2) ), 198.68 (𝐴 𝑔 (3) ), 322.81 (𝐴 𝑔 (4) ), 348.21 (𝐴 𝑔 (5) ), 354.94 (𝐵 𝑔 (3) ), 417.65 (𝐴 𝑔 (6) ), 477.63 (𝐴 𝑔 (7) ), 633.43 (𝐴 𝑔 (8) ), 650.8 (𝐵 𝑔 (5) ), 657.5 (𝐴 𝑔 (9) ) cm -1 , and longitudinal phonon-plasmon couples modes at 393.84 (L3) and 554.7 (L4) cm -1 53,54 . The full-width half maximum (FWHM) of the most intense 𝐴 𝑔 (6) peak of β-Ga2O3 is 14.35 cm -1…”

“…Recently there has been increasing research interest in gallium oxide (Ga2O3) based materials and devices 1 . The emergence of wide and ultrawide bandgap (UWBG) semiconductors such as III-nitrides (GaN, AlGaN), silicon carbide (SiC), diamond (C), including gallium oxide (Ga2O3) has spurred the development of the new class of light emitting diodes (LEDs) 2,3 , power semiconductor devices 4 , and deep-ultraviolet (UV) solar-blind photodetectors 5 . Despite the low thermal conductivity, Ga2O3 has a large Baliga-Figure-of-Merit 6,7 .…”

Deep‐Ultraviolet LEDs Incorporated with SiO2‐Based Microcavities Toward High‐Speed Ultraviolet Light Communication

“…On the one hand, the limited transmission distance is owing to the poor light output power of DUV LEDs. [19][20][21] With a slew of efforts in recent years, great progress has been made in materials quality [22,23] and doping asymmetry issues, [24][25][26][27] Optical wireless communication (OWC) in the deep-ultraviolet (DUV) band requires an efficient DUV light source with large bandwidth characteristics. In this work, a feasible approach is reported to enlarge the light output power as well as the bandwidth of a DUV light-emitting diode (LED) by embedding a SiO 2 -based microcavity on which an aluminum (Al) reflector is simultaneously deposited.…”

Self-Assembly Nanopillar/Superlattice Hierarchical Structure: Boosting AlGaN Crystalline Quality and Achieving High-Performance Ultraviolet Avalanche Photodetector

“…This parasitic reactions leads to defects and reduces the utilization efficiency of the growth source. These problems influence the epitaxial crystalline quality and lead to low mobility of carriers in AlGaN film, which will further affect the photoelectric properties of AlGaN-based devices . For instance, defects provide leakage and tunneling current channels, thus resulting in an excessive dark current of photodetectors.…”

“…These problems influence the epitaxial crystalline quality and lead to low mobility of carriers in AlGaN film, which will further affect the photoelectric properties of AlGaN-based devices. 24 For instance, defects provide leakage and tunneling current channels, thus resulting in an excessive dark current of photodetectors. Dislocations also act as nonradiative recombination centers, further reducing the internal quantum efficiency of light-emitting diodes.…”