Effect of quantum well shape and width on deep ultraviolet emission in AlGaN nanowire LEDs

Abstract

The effect of quantum well shape and width on the emission properties of nanowire ultraviolet LEDs is experimentally investigated. Nanowire LEDs are grown by plasma-assisted molecular beam epitaxy and their electroluminescence is compared. A two-to three-fold increase in optical output is observed from 5 nm wide parabolic quantum wells compared with square quantum wells. This increased output is attributed to the both increased electron-hole overlap in agreement with band edge modeling, and supports previous theoretical predictions of decreased Auger recombination due to softening of the potential well in parabolic quantum wells. It is experimentally observed that when the quantum well width is decreased to 2 nm, the parabolic quantum wells exhibit a twofold output improvement over the square wells at low injection. However, at high current injection, the parabolic and square quantum wells perform similarly. Peak emission wavelengths for the nanowire LEDs is pushed into the deep ultraviolet by decreasing the AlGaN quantum well width. The emission wavelength shifts from 315 to 290 nm when the width is decreased from nominally 5 to 0.5 nm.

Enhanced Performance of an AlGaN-Based Deep-Ultraviolet LED Having Graded Quantum Well Structure

“…It indicates that the value of LOP increases with decreasing QW thickness and finally the LOP value of the optimized LED with 3 nm-IAC grading QWs is more than twice higher than that of the reference sample. It is because that the values of Г e−hh in the QWs increase as the thickness of the QW decreased since the QCSE in the QWs becomes weaker [32]. It is worth noting that the LED with IAC grading QW still shows relatively better performance than reference Sample when the QW thickness increases from 3 nm to 5.5 nm, which is critical for fabricating high brightness AlGaN-based DUV LED.…”

Deep-ultraviolet integrated photonic and optoelectronic devices: A prospect of the hybridization of group III–nitrides, III–oxides, and two-dimensional materials

“…Polymeric materials, such as optically isotropic and stable amorphous fluorine resin [627,628] and graphene oxide (GO)based fluoropolymer composites [629] , may constitute a suitable substitute to other materials for the mass-production and packaging of Al x Ga 1-x N-based UV and DUV LEDs because of their decomposition characteristics below 330 nm [410,457,627,628] . DUV LED dies are generally flip-chip bonded on submounts with gold bumps, and polymer-based materials can be used between the submount and dies as underfilling materials, as well as for the rest of entire surfaces (as an encapsulation).…”

Semiconductor Solid‐Solution Nanostructures: Synthesis, Property Tailoring, and Applications

“…However, the emission intensity of semiconductor solid‐solutions gradually quenches with the increase of solubility to a certain extent. The luminescence depression of semiconductors is also harmful to the corresponding performance of optoelectronic nanodevices like LEDs and lasers . The main reason can be attributed to the increased nonradiation centers induced by the defects and the lattice deformation under high solubility condition.…”