AlGaN‐based ultraviolet light‐emitting diodes: challenges and opportunities

Abstract

Due to low power consumption, tunable wavelength and long lifetime ultraviolet light‐emitting diodes (UV LEDs) have found many applications in different fields such as health care, water disinfection, agriculture. In this review, we report different problems that lead to low external quantum efficiency of UV LEDs. We also report various challenges in the growth process of the UV LEDs such as increase in the dislocation density, which affects the optoelectronic performance of the devices. We also report the analysis of the two modes of light polarization, i.e. transverse electric and transverse magnetic in UV LEDs. Moreover, we also summarize various state‐of‐the‐art reported external quantum efficiencies, light output power and peak emission wavelengths in the three UV wavelength regimes, i.e. UV‐A, UV‐B and UV‐C LEDs.

Recent Advances in Packaging Technologies of AlGaN‐Based Deep Ultraviolet Light‐Emitting Diodes

“…[1][2][3][4] Besides, applications of deep UV in water purification and air disinfection are demonstrated as well. [5][6][7] In fact, UV has been proven to be a sterilizing agent since early times, it has been over a century since light therapy was presented by Niels Ryberg Finsen who won the Nobel Prize in Physiology or Medicine 1903 due to using concentrated beams of UV light to treat patients with lupus vulgaris with some success. [8] Since then, UV light is of widespread concern, and various UV devices are fabricated continuously, where medium and high-pressure mercury lamps are the most representative ones.…”

“…[9,10] These years, the UV mercury lamps have been widely applied in the field of UV curing, sensing, medical phototherapy, sterilization, and disinfection. [5][6][7]9,11] Although the UV mercury lamps have performed well but they have numerous disadvantages, including short lifetime, low efficiency, slow response, and fatal disadvantage of toxic mercury. [1] According to the requirement of the Minamata Convention on Mercury, there should be a decrease in the use (or eradicate) of a great deal of mercury-containing UV products by 2020.…”

Physical and technological analysis of the AlGaN-based UVC-LED: an extended discussion focused on cubic phase as an alternative for surface disinfection.

“…Even though, it is important to consider that crystalline sapphire or silicon carbide films (SiC) still suffer from excessive defects from substrate-film mismatches as thickness increases [88]. This is provoked, to a large extent, by the different lattice constants between the alloy components (AlN, InN, and GaN) [57,[89][90][91] and the change in the target Al content throughout the multilayer [92]. Moreover, due to its absorption, SiC is not explored enough [93], although, in order to face this drawback, UVC LED on SiC could be processed into a thin-film flip-chip to obtain high LEE [93].…”

The marvelous optical performance of AlGaN-based deep ultraviolet light-emitting diodes with AlInGaN-based last quantum barrier and step electron blocking layer

“…The real-world applications, such as water and air disinfection, currency screening, decontamination, photolithography, color display, and even for the disinfection of the SARS-CoV-2 virus, require a narrow UV band spectrum [1][2][3][4][5]. AlGaN-based semiconductor alloys have unique characteristics which make them a promising candidate for the above applications [6,7].…”