Development of high efficiency 255–355 nm AlGaN‐based light‐emitting diodes

Abstract

We report on the fabrication and characterization of high efficiency ultraviolet (UV) light emitting diodes (LEDs) with emission wavelength ranging from 255 to 355 nm. Epi-layers of UV LEDs were grown on AlGaN templates with sapphire substrates. Flip-chip configuration without removing sapphire is used for characterization of the UV LEDs. External quantum efficiencies (EQEs) over 3% were obtained for all the investigated wavelengths with maximum value reaching 5.1% for 280 nm LED. Under RT DC operation at a current of 500 mA, output powers of 38, 77, and 64 mW were measured for 257, 280, and 354 nm, respectively. By using enhanced light extraction technologies, such as, moth-eye structure on the back side of the sapphire substrate, we expect to improve these values by up to 50%.

Advantages of AlGaN-based deep ultraviolet light-emitting diodes with a superlattice electron blocking layer

“…and low output power of AlGaN-based UV LEDs still hinder their further development. The EQEs of the reported AlGaN deep UV LEDs with emission wavelengths from 280 to 350 nm are typically less than 10%, much lower than LEDs in the near UV and visible spectral range that use In x Ga 1Àx N materials [5][6][7]. The poor output performance of high Al content AlGaN UV LEDs is characterized by multiple problems.…”

Improving Performance of Algan‐Based Deep‐Ultraviolet Light‐Emitting Diodes by Inserting a Higher Al‐Content Algan Layer Within the Multiple Quantum Wells

“…However, till to now, realization of high‐efficiency DUV‐LEDs with wavelengths around 265 is still challenging . Many factors are responsible for that low efficiency, such as high threading dislocation density, very strong polarization effect, insufficient carrier confinement and poor hole injection efficiency .…”

Reduction of contact resistance in V‐based electrode for high AlN molar fraction n‐type AlGaN by using thin SiNx intermediate layer

“…AlGaN‐based UV light‐emitting diodes (UV LEDs) have many advantages, such as compactness, high efficiency, and wavelength selectivity, these devices are expected to replace conventional UV‐light sources based on glass lamps. So far, a high external quantum efficiency of deep UV LEDs ranging between UV‐B (emission wavelength 280–315 nm) and UV‐C (emission wavelength: lower than 280 nm) has already been reached . However, there are several issues in UV LEDs.…”