Surface Passivation of III–V GaAs Nanopillars by Low-Frequency Plasma Deposition of Silicon Nitride for Active Nanophotonic Devices

Abstract

low frequency (380 kHz) excitation plasma that enable intense bombardment of hydrogen, all seem to provide a combined active role in the passivation mechanism of the pillars by reducing the surface states.As a result, we observe up to a 29-fold increase of the photoluminescence (PL) integrated intensity for the best samples as compared to untreated nanopillars. X-ray photoelectron spectroscopy analysis confirms the best treatments show remarkable removal of gallium and arsenic native oxides. Time-resolved micro-PL measurements display nanosecond lifetimes resulting in a record-low surface recombination velocity of ~1.1×10 4 cm s -1 for dry etched GaAs nanopillars. We achieve robust, stable and long-term passivated nanopillar surfaces which creates expectations for remarkable high internal quantum efficiency (IQE>0.5) in GaAs nanoscale light-emitting diodes. The enhanced performance paves the way to many other nanostructures and devices such as miniature resonators, lasers, photodetectors and solar cells opening remarkable prospects for GaAs active nanophotonic devices.ultralow output powers (in the nW or even pW range), 3,10,11 which makes nanoLEDs challenging for practical optical systems. Taking the example of III-V nanopillars, and neglecting losses related with metallic structures in metal-dielectric or plasmonic nanocavites, the main reasons for the extremely low EQEs are two-fold. Firstly, coupling the light output efficiently to a nanowaveguide, 11 or a plasmonic waveguide, 3 remains a challenge when the area of the light source is reduced to the deep sub-µm. 2 Secondly, at these small scales non-radiative effects in III-V materials, specifically surface-related properties, become more important as the surface-to-volume ratio increases substantially. In this work, we devote our attention to the role of the non-radiative effects in the performance of III-V gallium arsenide (GaAs) light-emitting subwavelength devices.Among the wide range of III-V materials available for active nanophotonic devices, the GaAs/Al-GaAs is one of the most studied and a key compound material for photonics, 4,15-18 providing optical emission and absorption in a wide range of wavelengths spanning from the visible to near-infrared (NIR).GaAs has recently been notable in many photonic applications such as 3D sensing using GaAs-based lasers, NIR-LEDs and visible red-orange-yellow LEDs for displays. However, the surface of GaAs-based materials and their interfaces with dielectrics tend to host large densities of electronically active defects (or dangling bonds). 19 As a result, at ambient conditions, an oxide layer is formed on the surface of the GaAs (e.g. Ga2O3 and As2O3), which leads to charge trapping. 20 Importantly, when semiconductors are nanostructured, namely using top-down dry etching, the plasma reactive etching process can induce additional surface damages, 21 such as surface roughness due to ion bombardment, surface contamination due to polymer deposition, or surface stoichiometry change due to preferential etching. Overall...

Experimental Observation of Purcell-Enhanced Spontaneous Emission in a Single-Mode Plasmonic Nanocavity

“…The device performance can be further improved via surface passivation to reduce surface recombination velocity and increase the cavity Q. 38 ■ METHODS Device Fabrication. The devices are fabricated from an InP wafer, with 300 nm epitaxially grown InGaAsP MQW covered by a 10 nm InP overlayer.…”

“…Our experimental results validate the expected device performance, showing a high Purcell factor of 74, which corresponds to a modulation bandwidth of 6.65 GHz. The device performance can be further improved via surface passivation to reduce surface recombination velocity and increase the cavity Q . This demonstration serves as a crucial prototype for fast and efficient nanoscale light sources, offering promising prospects for future high-speed optical interconnects.…”

Brain-inspired nanophotonic spike computing: challenges and prospects

“…The key neuron-like functions of this nanoRTD-LED emitter architecture was first proposed in [78]. In this Section, we summarize the main properties of the nanoLED neuron emitters, as well as recent advances reported elsewhere in realizing and improving such nanoemitters, namely increasing their output power enabled by light extraction [79], and surface passivation [80] methods.…”

“…Passivation of GaAs with silicon nitride (Si x N y ) has been proposed to improve GaAs electrical performance [87]. Recently, it has been demonstrated that surface passivation using a combination of ammonium sulphide chemical treatment followed by encapsulation with a thin layer of Si x N y (80 nm) deposited by low-frequency plasma enhanced chemical vapour deposition (LF-PECVD) can result in improved optical properties of nanopillar LEDs [80]. The results show that passivated GaAs nanopillar surfaces are robust, stable, and long-lasting.…”

“…The passivation treatment used ammonium sulphide followed by SixNy coating deposited by low-frequency PECVD. A schematic of the best treatment procedure is shown inset, displaying the pillar coated with a SixNy dielectric (Reproduced from[80]. CC BY 4.0.…”