Effect of HfO₂ Passivation Layer on Light Extraction Efficiency of AlInN Nanowire Ultraviolet Light-Emitting Diodes

Abstract

One of the probable reasons behind the limitation of light extraction efficiency (LEE) in III-nitride nanowire (NW) deep ultraviolet (UV) light-emitting diodes (LEDs) is the presence of the high surface density states that significantly contribute to the non-radiative recombination near the surface. Herein, we investigate the LEE of a single AlInN NW UV LED in the entire UV wavelength regime using finite-difference time-domain simulations. It is found that these LEDs favor transverse-magnetic (TM) polarized LEE over transverse-electric (TE) polarized emission. Further, we examine the role of the HfO2 surface passivation layer in the improvement of LEE of AlInN NW LED at ~282 nm wavelength. Our results show that the TM-polarized LEE of such LED without any passivation is only ~25.2%, whereas the maximum recorded LEE is ~40.6% with the utilization of 40 nm HfO2 passivation layer. This study provides a promising approach for enhancing the LEE of NW UV LEDs.

InGaN-based green micro-LED efficiency enhancement by hydrogen passivation of the p-GaN sidewall

“…14) On the other hand, the sidewall passivation layer suppresses any further chemical reactions of the exposed sidewall with air or chemicals involved in further device processing. Materials used as the passivation layer are Al 2 O 3 , 15,16) SiO 2 , 17) HfO 2 , 18) ZnO, 19) and AlN. 20) This work proposes a different approach to overcoming mesa sidewall damage by blocking the current injection into the device's sidewall region.…”

Efficiency improvement by using metal–insulator-semiconductor structure in InGaN/GaN micro-light-emitting diodes

“…For the former method, a better deposition method is required. Compared to PECVD, atomic layer deposition (ALD) is a better deposition method with higher resolution [ 8 – 10 , 22 – 25 ]. Due to the one-molecule-layer deposition per cycle process, ALD-passivated layers exhibit superior conformal coverage, resulting in more substantial suppression of surface recombination compared to PECVD-passivated layers.…”

(Invited) Enhanced Efficiency of AlInN Nanowire Ultraviolet Light-Emitting Diodes Using Photonic Crystal Structures

“…Moreover, source power monitors are placed around the single dipole source to measure the total power generated in the active region accurately. Finally, we have calculated the LEE of nanowire LED which is the ratio of the light output power measured by the output power monitors to the total emitted power in active region measured by the source power monitor [21]. First, the LEE of AlInN nanowire UV LED is investigated for both TE-and TMpolarizations as a function of nanowire diameter.…”