Low Extinction Research Articles

Atomically sharp interface enabled ultrahigh-speed non-volatile memory devices.

The development of high-performance memory devices has played a key role in the innovation of modern electronics. Non-volatile memory devices have manifested high capacity and mechanical reliability as a mainstream technology; however, their performance has been hampered by low extinction ratio and slow operational speed. Despite substantial efforts to improve these characteristics, typical write times of hundreds of micro- or milliseconds remain a few orders of magnitude longer than that of their volatile counterparts. Here we demonstrate non-volatile, floating-gate memory devices based on van der Waals heterostructures with atomically sharp interfaces between different functional elements, achieving ultrahigh-speed programming/erasing operations in the range of nanoseconds with extinction ratio up to 1010. This enhanced performance enables new device capabilities such as multi-bit storage, thus opening up applications in the realm of modern nanoelectronics and offering future fabrication guidelines for device scale up.

Airborne Measurements of Contrail Ice Properties—Dependence on Temperature and Humidity

AbstractThe largest share in the climate impact of aviation results from contrail cirrus clouds. Here, the dependence of microphysical contrail ice properties and extinction on temperature and humidity is investigated. Contrail measurements were performed at various altitudes during the 2018 ECLIF II/NDMAX campaign with the NASA DC‐8 chasing the DLR A320. Ice number concentrations and contrail extinction coefficients are largest at altitudes near 9.5 km, typical for short‐ and medium‐range air traffic. At higher altitudes near 11.5 km, low ambient water vapor concentrations lead to smaller contrail particle sizes and lower extinction coefficients. In addition, contrails were detected below 8.2 km near the Schmidt‐Appleman contrail formation threshold temperature. Here, only a small fraction (<15%) of the emitted soot particles were activated into ice. Our observations enhance the understanding of contrail formation near the formation threshold and give a glimpse on the altitude dependence of climate‐relevant contrail properties.

Derivation of Dielectric Constant and Debye Length of Amorphous Si–In–Zn–O by Analyzing Optical Coefficients

Highly transparent amorphous Si-doped InZnO (SIZO) thin film was deposited on glass substrate by RF magnetron sputtering at room temperature. The optical constants of SIZO thin film were measured by the ellipsometry. Various parameters were calculated that result from using refractive index and extinction coefficient. In SIZO material system, dielectric constant of real part (er) value are larger than dielectric constant of imaginary part (ei) value due to the low extinction coefficient (k) value. In addition, the optical bandgap also showed 3.45 eV calculated using the (αhv)2 vs hv plot. From this result, the transparency of the SIZO thin film in the visible light region was confirmed, the Debye length of the SIZO thin film transistor was calculated, and the change in the effective carrier concentration was confirmed.

Edge‐Orientation Dependent Nanoimaging of Mid‐Infrared Waveguide Modes in High‐Index PtSe2

AbstractAll‐dielectric nanophotonics is a rapidly developing field that employs high‐index low‐loss dielectric materials to boost light–matter interactions at the nanoscale. This is owing to their potential in achieving low‐loss optical responses and the coexistence of strong enhancement of electric and magnetic fields, which are absent in their plasmonic counterparts. Transition‐metal dichalcogenides (TMDCs) have been utilized for high‐index dielectric Mie nanoresonators in the visible to near‐infrared spectral range due to their high in‐plane and out‐of‐plane optical anisotropy, excitonic effect, and high‐index properties. However, high‐index materials for mid‐infrared (MIR) nanophotonics are still highly sought after. Here, it is shown that PtSe2, a group‐10 TMDC, could support dielectric waveguide modes in MIR despite its semimetallic nature. It is revealed that PtSe2optically acts as a dielectric material with a high refractive index of ≈5 and a low extinction coefficient in the MIR region. The value is among the highest in the low‐loss TMDCs and mainstream dielectric materials. A comprehensive sample‐edge‐orientation dependent nanoimaging together with spectroscopic nanoimaging characterization of the PtSe2 allows the extraction of the dispersion relations of the modes, from which the velocity parameters could be determined. This work paves the way for high‐performance MIR devices via high‐index PtSe2‐based nanostructures.

CO+ as a probe of the origin of CO in diffuse interstellar clouds

Context. The chemistry of the diffuse interstellar medium is driven by the combined influences of cosmic rays, ultraviolet (UV) radiation, and turbulence. Previously detected at the outer edges of photodissociation regions and formed from the reaction of C+ and OH, CO+ is the main chemical precursor of HCO+ and CO in a thermal, cosmic-ray, and UV-driven chemistry. Aims. Our aim was to test whether the thermal cosmic-ray and UV-driven chemistry is producing CO in diffuse interstellar molecular gas through the intermediate formation of CO+. Methods. We searched for CO+ absorption with the Atacama Large Millimeter Array toward two quasars with known Galactic foreground absorption from diffuse interstellar gas, J1717-3342 and J1744-3116, targeting the two strongest hyperfine components of the J = 2−1 transition near 236 GHz. Results. We could not detect CO+ but obtained sensitive upper limits toward both targets. The derived upper limits on the CO+ column densities represent about 4% of the HCO+ column densities. The corresponding upper limit on the CO+ abundance relative to H2 is <1.2 × 10−10. Conclusions. The non-detection of CO+ confirms that HCO+ is mainly produced in the reaction between oxygen and carbon hydrides, CH2+ or CH3+, induced by suprathermal processes, while CO+ and HOC+ result from reactions of C+ with OH and H2O. The densities required to form CO molecules at low extinction are consistent with this scheme.

Estimating the impacts of habitat loss induced by urbanization on bird local extinctions

Habitat loss and fragmentation can be long-term processes driving extinction debts, especially in cities. Because of a lack of temporal data, long-term impacts are generally investigated less frequently than short-term impacts. However, these effects are equally important for understanding biodiversity loss. We developed a Bayesian Island Biogeography model combining historical imagery and current species distribution to investigate the long-term impacts of urbanization-induced habitat loss and isolation on birds. We surveyed 101 bird species in 43 urban forest patches in a South American city with different combinations of size, isolation, and time since the last abrupt change in area. Based on the current and historical landscape configuration, we estimated the temporal dynamics between species extinction rate and area, and between immigration rate and isolation. Additionally, we used model parameters to forecast bird extinction debts. Large patches had lower extinction rates than small patches, and immigration rates were lower in more isolated patches. Furthermore, current bird species richness was better explained by current landscape configuration than by past configuration, suggesting that birds rapidly respond to changes in urban landscapes and there are no apparent extinction debts. Indeed, we found that habitat loss reduces species diversity to a new equilibrium in relatively short period (less than 10 years), and model projections indicate that bird richness will remain similar to the present if patch area is maintained. Habitat loss is the most important cause of species local extinctions in urban areas, and tropical cities could rapidly promote biodiversity by restoring forest cover.

VVV survey near-infrared colour catalogue of known variable stars

Context. The Vista Variables in the Via Lactea (VVV) near-infrared variability survey explores some of the most complex regions of the Milky Way bulge and disk in terms of high extinction and high crowding. Aims. We add a new wavelength dimension to the optical information available at the American Association of Variable Star Observers International Variable Star Index (VSX-AAVSO) catalogue to test the VVV survey near-infrared photometry to better characterise these objects. Methods. We cross-matched the VVV and the VSX-AAVSO catalogues along with Gaia Data Release 2 photometry and parallax. Results. We present a catalogue that includes accurate individual coordinates, near-infrared magnitudes (ZYJHKs), extinctions AKs, and distances based on Gaia parallaxes. We also show the near-infrared CMDs and spatial distributions for the different VSX types of variable stars, including important distance indicators, such as RR Lyrae, Cepheids, and Miras. By analysing the photometric flags in our catalogue, we found that about 20% of the stars with measured and verified variability are flagged as non-stellar sources, even when they are outside of the saturation and/or noise regimes. Additionally, we pair-matched our sample with the VIVA catalogue and found that more than half of our sources are missing from the VVV variability list, mostly due to observations with low signal-to-noise ratio or photometric problems with a low percentage due to failures in the selection process. Conclusions. Our results suggest that the current knowledge of the variability in the Galaxy is biased to nearby stars with low extinction. The present catalogue also provides the groundwork for characterising the results of future large variability surveys such as the Vera C. Rubin Observatory Legacy Survey of Space and Time in the highly crowded and reddened regions of the Galactic plane, as well as follow-up campaigns for characterising specific types of variables. The analysis of the incorrectly flagged stars can be used to improve the photometric classification of the VVV data, allowing us to expand the amount of data considered useful for science purposes. In addition, we provide a list of stars that are missed by the VIVA procedures for which the observations are good and which were missed due to some failure in the VIVA selection process.

Looking for Obscured Young Star Clusters in NGC 1313

Abstract Using recently acquired Hubble Space Telescope NIR observations (J, Paβ, and H bands) of the nearby galaxy NGC 1313, we investigate the timescales required by a young star cluster to emerge from its natal cloud. We search for extincted star clusters, potentially embedded in their natal cloud as either (1) compact sources in regions with high Hα/Paβ extinctions or (2) compact H ii regions that appear as point-like sources in the Paβ emission map. The NUV–optical–NIR photometry of the candidate clusters is used to derive their ages, masses, and extinctions via a least-χ 2 spectral energy distribution broad- and narrowband fitting process. The 100 clusters in the final samples have masses in the range and moderate extinctions, E(B − V) ≲ 1.0 mag. Focusing on the young clusters (0–6 Myr), we derive a weak correlation between extinction and age of the clusters. Almost half of the clusters have low extinctions, E(B − V) < 0.25 mag, already at very young ages (≤3 Myr), suggesting that dust is quickly removed from clusters. A stronger correlation is found between the morphology of the nebular emission (compact, partial or absent, both in Hα and Paβ) and cluster age. Relative fractions of clusters associated with a specific nebular morphology are used to estimate the typical timescales for clearing the natal gas cloud, resulting in between 3 and 5 Myr, ∼1 Myr older than what was estimated from NUV–optical-based cluster studies. This difference hints at a bias for optical-only-based studies, which James Webb Space Telescope will address in the coming years.

Cosmic ray sputtering yield of interstellar ice mantles

Aims. Cosmic-ray-induced sputtering is one of the important desorption mechanisms at work in astrophysical environments. The chemical evolution observed in high-density regions, from dense clouds to protoplanetary disks, and the release of species condensed on dust grains, is one key parameter to be taken into account in interpretations of both observations and models. Methods. This study is part of an ongoing systematic experimental determination of the parameters to consider in astrophysical cosmic ray sputtering. As was already done for water ice, we investigated the sputtering yield as a function of ice mantle thickness for the two next most abundant species of ice mantles, carbon monoxide and carbon dioxide, which were exposed to several ion beams to explore the dependence with deposited energy. Results. These ice sputtering yields are constant for thick films. It decreases rapidly for thin ice films when reaching the impinging ion sputtering desorption depth. An ice mantle thickness dependence constraint can be implemented in the astrophysical modelling of the sputtering process, in particular close to the onset of ice mantle formation at low visual extinctions.

All-Dielectric Color Filter with Ultra-Narrowed Linewidth.

In this paper, a transmissive color filter with an ultra-narrow full width at half of the maximum is proposed. Exploiting a material with a high index of refraction and an extremely low extinction coefficient in the visible range allows the quality factor of the filter to be improved. Three groups of GaP/SiO2 pairs are used to form a Distributed Brag reflector in a symmetrical Fabry-Pérot cavity. A band-pass filter which is composed of ZnS/SiO2 pairs is also introduced to further promote the purity of the transmissive spectrum. The investigation manifests that a series of tuned spectrum with an ultra-narrow full width at half of the maximum in the full visible range can be obtained by adjusting the thickness of the SiO2 interlayer. The full width at half of the maximum of the transmissive spectrum can reach 2.35 nm. Simultaneously, the transmissive efficiency in the full visible range can keep as high as 0.75. Our research provides a feasible and cost-effective way for realizing filters with ultra-narrowed linewidth.

Evolutionary trends of body size and hypsodonty in notoungulates and their probable drivers

Members of the Order Notoungulata are among the most diverse and common mammals in South America during the Cenozoic. Several lineages within notoungulates (e.g., suborders Typotheria and Toxodontia) show a tendency for increased body sizes and hypsodonty during the last 50 Myr. However, the timing, evolutionary mode, and drivers of such tendencies are not entirely understood. In this paper, we use an extensive database of notoungulate fossil occurrences and body mass and hypsodonty estimates to characterize the evolutionary mode of these two phenotypic traits over time, test the extent to which several factors (e.g., development of open environments in the south of South America) have influenced it through time, and investigate whether large trait values were selected through elevated origination or reduced extinction rates. Our results demonstrate that most of the major notoungulate clades evolved toward larger body sizes (up 1500 kg) and higher tooth crown, from a small and low-crowned tooth ancestor, in a punctuated mode. We also show that body mass and the hypsodonty in typotherians and toxodonts had a coupled evolutionary history. Species sorting was a relevant macroevolutionary process in some notoungulate clades, as taxa with high teeth crown and body mass had lower extinction rates. Finally, the development of the hypsodonty in notoungulates must reflect repeated and quick instances of adaptive responses to the increased availability of volcanic or other terrigenous particles, within the broad context of the SSA Cenozoic Andean mountain building.

Hunting pressure is a key contributor to the impending extinction of Bornean wild cattle

Widespread and unregulated hunting of ungulates in Southeast Asia is resulting in population declines and localised extinctions. Increased access to previously remote tropical forest following logging and changes in land-use facilitates hunting of elusive wild cattle in Borneo, which preferentially select secluded habitat. We collated the first population parameters for the Endangered Bornean banteng Bos javanicus lowi and developed population models to simulate the effect of different hunting offtake rates on survival and the recovery of the population using reintroduced captive-bred individuals. Our findings suggest that the banteng population in Sabah is geographically divided into 4 management units based on connectivity: the Northeast, Sipitang (West), Central and Southeast, which all require active management to prevent further population decline and local extinction. With only 1% offtake, population growth ceased in the Northeast and Sipitang. In the Southeast and Central units, growth ceased at 2 and 4% offtake, respectively. Extinction was estimated at 21-39 yr when offtake was 5%, occurring first in Sipitang and last in the Central unit. Supplementing the population with captive-bred individuals suggested that inbreeding was likely to limit population growth if using ≤20 founder individuals. Translocating 2 individuals for a 10 yr period, starting after 20 yr of captive breeding resulted in a faster population recovery over 100 yr and a lower extinction probability. Our results suggest that shielding the population against further losses from hunting will be key to their survival in the wild, provided that active management in the form of captive breeding is developed in the interim.

Mouse eradication is required to prevent local extinction of an endangered seabird on an oceanic island

AbstractPetrels (Procellariidae) are a highly diverse family of seabirds, many of which are globally threatened due to the impact of invasive species on breeding populations. While predation by invasive cats and rats has led to the extinction of petrel populations, the impact of invasive house mice Mus musculus is slower and less well documented. However, mice impact small burrow‐nesting species such as MacGillivray’s prion Pachyptila macgillivrayi, a species classified as endangered because it has been extirpated on islands in the Indian Ocean by introduced rodents. We use historic abundance data and demographic monitoring data from 2014 to 2020 to predict the population trajectory of MacGillivray’s prion on Gough Island with and without a mouse eradication using a stochastic integrated population model. Given very low annual breeding success (0.01 fledglings per breeding pair in ‘poor’ years (83%) or 0.38 in ‘good’ years (17%), n = 320 nests over 6 years) mainly due to mouse predation, our model predicted that the population collapsed from ~3.5 million pairs in 1956 to an estimated 175,000 pairs in 2020 despite reasonably high adult survival probability (ϕ = 0.901). Based on these parameters, the population is predicted to decline at a rate of 9% per year over the next 36 years without a mouse eradication, with a 31% probability that by 2057, the MacGillivray’ prion population would become extremely vulnerable to extinction. Our models predict population stability (λ = 1.01) and a lower extinction risk (<10%) if mouse eradication on Gough Island restores annual breeding success to 0.519, which is in line with that of closely related species on predator‐free islands. This study demonstrates the devastating impacts that introduced house mice can have on small burrowing petrels and highlights the urgency to eradicate invasive mammals from oceanic islands.

Evaluating Fish Rescue as a Drought Adaptation Strategy Using a Life Cycle Modeling Approach for Imperiled Coho Salmon

AbstractProjected intensification of drought as a result of climate change may reduce the capacity of streams to rear fish, exacerbating the challenge of recovering salmonid populations listed under the Endangered Species Act. Without management intervention, some stocks will likely go extinct as stream drying and fragmentation reduce juvenile survival to unsustainable levels. To offset drought‐related mortality, fish rescue programs have proliferated, whereby juvenile salmonids are captured and transferred to off‐site rearing facilities. However, the efficacy of this potential conservation tool remains poorly understood. We developed a life cycle model to examine the implications of fish rescue on the abundance of Coho Salmon Oncorhynchus kisutch across serial life stages. The simulation model examines scenarios with varying quantities of rescued fish, time in captivity, drought severity, and reduced smolt‐to‐adult return rates. Our results indicate that fish rescue can increase the abundance of adults and lower extinction risk, particularly for fish held in captivity for a full year. However, fish rescue can also decrease the abundance of adults and increase extinction risk if fish are held only for summer and there is limited winter habitat. We found that when fish rescue did increase returns, it functioned more like a stock enhancement program than a drought mitigation tool and it would likely lead to consecutive generations of captive rearing, which has been shown to have negative effects on fitness. We translated our model into an R Shiny application (https://shiny.wdfw‐fish.us/CohoPopulationDynamics/) that allows users to explore how fish rescue affects Coho Salmon population dynamics through customized parameterization of the model to represent different systems or different assumptions about the effects of fish rescue.

Milky Way Tomography with the SkyMapper Southern Survey. II. Photometric Recalibration of SMSS DR2

Abstract We apply the spectroscopy-based stellar-color regression (SCR) method to perform an accurate photometric recalibration of the second data release from the SkyMapper Southern Survey (SMSS DR2). From comparison with a sample of over 200,000 dwarf stars with stellar atmospheric parameters taken from GALAH+ DR3 and with accurate, homogeneous photometry from Gaia DR2, zero-point offsets are detected in the original photometric catalog of SMSS DR2, in particular for the gravity- and metallicity-sensitive uv bands. For the uv bands, the zero-point offsets are close to zero at very low extinction, and then steadily increase with E(B − V), reaching as large as 0.174 and 0.134 mag respectively, at E(B − V) ∼ 0.5 mag. These offsets largely arise from the adopted dust term in the transformations used by SMSS DR2 to construct photometric calibrators from the ATLAS reference catalog. For the gr bands, the zero-point offsets exhibit negligible variations with the E(B − V) of Schlegel et al. due to their tiny coefficients on the dust term in the transformation. Our study also reveals small but significant spatial variations of the zero-point offsets in all uvgr bands. External checks using Strömgren photometry, WD loci, and the SDSS Stripe 82 standard-star catalog independently confirm the zero-points found by our revised SCR method.

High mobility Ti, Zr and Ga-codoping In2O3 transparent conductive oxide films prepared at low temperatures

High mobility transparent conductive Zr, Ti and Ga-doped indium oxide (ITGZO) films were deposited by radio frequency (RF) magnetron sputtering method at the low deposition temperature. The effects of deposition temperatures on structural, electrical, and optical properties of ITGZO films were investigated in this work. High mobility of 94 cm2/V S was achieved at the deposition temperature of 70 °C along with the annealing process. Furthermore, the optical transmittance of ITGZO films has increased by 18% at the infrared wavelength region from 1500 to 2580 nm; compared to the typical Sn-doped indium oxide (ITO) films, this excellent transmittance is mainly attributed to the less free carrier absorption (FCA) thanks to the low carrier concentration of less than 2.0 × 1020 cm−3. In addition, the surface morphology of ITGZO films demonstrated that Ga element would precipitate on the film surface when oxygen was insufficient during the film growth, which indicates that Ga element exists as an oxidation state rather than interstitial atom in ITGZO films; correspondingly, the impurity ion scattering of carriers would be effectively suppressed, which accounts for the high mobility of ITGZO films. Moreover, ITGZO film shows a very low extinction coefficient (k) of 10–4 at 633 nm after annealing, which implies almost zero absorption loss from ITGZO films. Based on the higher mobility and better optical properties, it is expected that ITGZO film is a promising alternative material substituting for the typical ITO film in the advanced optoelectronic devices.

Validation of SAGE III/ISS Solar Water Vapor Data With Correlative Satellite and Balloon‐Borne Measurements

AbstractSince June 2017, the Stratospheric Aerosol and Gas Experiment III instrument on the International Space Station (SAGE III/ISS) has been providing vertical profiles of upper tropospheric to stratospheric water vapor (SWV) retrieved from solar occultation transmission measurements. The goal of this study is to evaluate the publicly released SAGE III/ISS beta version 5.1 WV retrieval through intercomparison with independent satellite‐ and balloon‐based measurements, and to present recommendations for SAGE III/ISS data quality screening criteria. Overall, we find that SAGE III/ISS provides high quality water vapor measurements. Low quality profiles are predominately due to retrieval instabilities in the upper stratosphere that cause step‐like changes in the profile, and aerosol/cloud‐related interferences (below ∼20 km). Above 35 km, the retrieved uncertainty and noise in the data rapidly grow with increasing altitude due to relatively low extinction signal from water vapor. Below the tropopause, retrieved uncertainty increases with decreasing altitude due to enhanced molecular scattering and aerosol extinction. After screening low‐quality data using the procedures described herein, SAGE III/ISS WV is shown to be in good agreement with independent satellite and balloon‐based measurements. From 20 to 40 km, SAGE III/ISS WV v5.1 data exhibit a bias of 0.0 to −0.5 ppmv (∼10%) relative to the independent data, depending on the instrument and altitude. Despite its status as a beta version, the level of SAGE III/ISS WV agreement with independent data is similar to previous SAGE instruments, and therefore the data are suitable for scientific studies of SWV.

Numerical study of the influence of thermal radiation on measuring semi-transparent thermal insulation material with hot wire method

Semi-transparent thermal insulation material has very low extinction coefficient and will transmit infrared spectrum within some wavelength range. When measuring the thermal conductivity (TC) of such kinds of material with transient methods, both heat conduction and thermal radiation occur within material. Transient hot wire (HW) method is a widely used method for thermal insulation measurement. It is developed with the assumption that heat only transfers via conduction. Since thermal radiation within low density thermal insulation material is a pronounced heat transfer mode at high temperature, the TC of radiation participating medium measured by HW method might be incorrect. To reveal the inconsistency between test theory and practical heat transfer process when measuring semi-transparent thermal insulation material with HW method, the transient conduction and radiation coupled heat transfer process is simulated numerically. The uncertainty caused by thermal radiation is investigated for material with different extinction coefficient at various temperature. The deviation increases with the increment of temperature and decreases with increment of extinction coefficient compared to results obtained from the one dimensional (1D) steady state method. The numerical analysis indicates that the TC of thermal insulation material with low extinction ability measured by HW method is overestimated at high temperature.

Dependence of characteristics of Hf(M)SiBCN (M = Y, Ho, Ta, Mo) thin films on the M choice: Ab-initio and experimental study

Amorphous HfMSiBCN materials (M = Y, Ho, Ta, Mo or an enhanced Hf content instead of any other M) are investigated by ab-initio calculations and magnetron sputtering. We focus on combining the high-temperature stability and oxidation resistance of these materials with optimised mechanical, optical and electrical properties. First, we predict the corresponding trends by calculating the effect of the M choice and fraction on formation energy (Eform) and mechanical properties of MN and HfxM1–xN crystals. We discuss the dependence of Eform(HfxM1–xN) on the crystal structure and the distribution of Hf and M in the metal sublattice. The mechanical properties calculated for MN correlate with those measured for HfMSiBCN. The driving force towards N incorporation, decreasing with the periodic-table group number of M according to the calculated Eform(MN), correlates with the measured increasing electrical conductivity and extinction coefficient of HfMSiBCN. Second, we model the amorphous HfMSiBCN materials themselves by ab-initio molecular dynamics. The calculated band gap, localisation of electronic states and bonding preferences of M also correspond to the increasing metallicity with respect to the periodic-table group number of M and confirm the possibility of predicting the trends in characteristics of HfMSiBCN using those of MN. Third, we study the measured HfMSiBCN properties as functions of each other and identify sputter target compositions leading to hard films with high electrical conductivity at a relatively low extinction coefficient. The results are important for the design of hard, conductive and/or transparent high-temperature coatings.

The VVV near-IR galaxy catalogue beyond the Galactic disc

ABSTRACT Knowledge about the large-scale distribution of galaxies is far from complete in the Zone of Avoidance (ZoA), which is mostly due to high interstellar extinction and to source confusion at lower Galactic latitudes. Past near-infrared (NIR) surveys, such as the Two Micron All Sky Survey (2MASS), have shown the power of probing large-scale structure at these latitudes. Our aim is to map the galaxy distribution across the Southern Galactic plane using the VISTA Variables in the Vía Láctea Survey (VVV), which reach 2–4 mag deeper than 2MASS. We used SExtractor+PSFEx to identify extended objects and to measure their sizes, the light concentration index, magnitudes, and colours. Morphological and colour constraints and visual inspection were used to confirm galaxies. We present the resulting VVV NIR Galaxy Catalogue (VVV NIRGC) of 5563 visually confirmed galaxies, of which only 45 were previously known. This is the largest catalogue of galaxies towards the Galactic plane, with 99 per cent of these galaxies being new discoveries. We found that the galaxy density distribution closely resembled the distribution of low interstellar extinction of the existing NIR maps. We also present a description of the 185 2MASS extended sources observed in the region, of which 16 per cent of these objects had no previous description, which we have now classified. We conclude that interstellar extinction and stellar density are the main limitations for the detection of background galaxies in the ZoA. The VVV NIRGC is a new data set providing information for extragalactic studies in the Galactic plane.