Ultraviolet Research Articles

Cosmic rays cannot explain the high ionisation rates in the Galactic centre

The Htwo ionisation rate in the central molecular zone, located in the Galactic centre, is estimated to be ζ∼2 s based on observations of H_3^+ lines. This value is two to three orders of magnitude larger than that measured anywhere else in the Galaxy. Due to the high density of the gas in the central molecular zone, UV and X-ray photons do not penetrate this region. Hence, cosmic rays are expected to be the exclusive agents of ionisation. A high cosmic-ray density has been invoked to explain the unusually high ionisation rate. However, this excess is not seen in the γ-ray emission from this region, which is produced by high-energy cosmic rays. Therefore, an excess is expected only in the low-energy cosmic-ray spectrum. Here, we derive constraints on this hypothetical low-energy component in the cosmic-ray spectra, and we question its plausibility. To do so, we numerically solved the cosmic-ray transport equation in the central molecular zone, considering spatial diffusion, advection in the Galactic wind, re-acceleration in the ambient turbulence, and energy losses due to interactions with matter and radiation in the interstellar medium. We derived stationary solutions under the assumption that cosmic rays are continuously injected by a source located in the Galactic centre. The high-energy component in the cosmic-ray spectrum was then fitted to available γ-ray and radio data, and a steep low-energy component was added to the cosmic-ray spectrum to explain the large ionisation rates. We find that injection spectra of p^-7 for protons below p_ enh,p c≃780 MeV and p^-5.2 for electrons below p_ enh,e c=1.5 GeV are needed to reach the observed ionisation rates. This corresponds to a cosmic-ray power of the order of ∼10^ erg s injected at the Galactic centre. Not only is this unrealistic, but it is also impossible to reproduce a constant ionisation rate across the region, as observations suggest. We conclude that cosmic rays alone cannot explain the high ionisation rates in the Galactic centre.

Pigmented Superficial Basal Cell Carcinoma of the Nipple-Areola Complex: A Case Report

Introduction: Basal cell carcinoma (BCC) is the most common type of skin malignancy, accounting for approximately 80% of all non-melanoma skin cancers (NMSCs). Ultraviolet (UV) exposure is a significant risk factor for BCC development, which typically occurs in sun-exposed areas. BCC arising in non-sun-exposed regions, such as the nipple-areola complex (NAC), is exceedingly rare, with fewer than 100 cases reported globally. This report describes a case of pigmented superficial BCC in the NAC of a 76-year-old Asian woman. Case Presentation: A 76-year-old Asian female presented with a 5-year history of a slowly enlarging lesion on her left breast, with recent rapid growth. Physical examination revealed a 10 mm × 8 mm blue-gray, pearl-like plaque on the NAC. Histopathology confirmed pigmented superficial BCC. Preoperative imaging, including breast ultrasound, chest computed tomography (CT), SPECT-CT, and axillary lymph node ultrasound, showed no evidence of metastasis. The patient underwent standard surgical excision with a 10 mm margin, followed by pathologic evaluation, confirming clear margins. The patient was discharged on the second postoperative day and remained asymptomatic at a 3-month follow-up. Conclusion: Pigmented superficial BCC of the NAC is an uncommon presentation due to the area’s minimal sun exposure and lack of pilosebaceous units. This case underscores the importance of considering BCC in non-sun-exposed areas, particularly in elderly patients. While nonsurgical options such as photodynamic therapy may offer superior esthetic outcomes, the patient’s financial constraints led to the selection of a cost-effective surgical excision, which successfully eliminated the tumor.

XUV yield optimization of two-color high-order harmonic generation in gases

Abstract We perform an experimental two-color high-order harmonic generation study in argon with the fundamental of an ytterbium ultrashort pulse laser and its second harmonic. The intensity of the second harmonic and its phase relative to the fundamental are varied while keeping the total intensity constant. We extract the optimum values for the relative phase and ratio of the two colors which lead to a maximum yield enhancement for each harmonic order in the extreme ultraviolet spectrum. Within the three-step model, the yield maximum can be associated with a flat electron return time versus return energy distribution. An analysis of different distributions allows to predict the required relative two-color phase and ratio for a given harmonic order, total laser intensity, fundamental wavelength, and ionization potential.

Potential of Natural-Based Sun Protection Factor (SPF): A Systematic Review of Curcumin as Sunscreen

Exposure to ultraviolet (UV) radiation from the sun significantly damages the skin, leading to premature aging, hyperpigmentation, and oxidative stress that disrupts skin homeostasis. UV radiation increases the production of reactive oxygen species (ROS), accelerating skin deterioration. Although sunscreens remain the primary method for UV protection, chemical-based formulations are often associated with side effects, such as allergic reactions and acne. To address these concerns, the inclusion of natural ingredients in sunscreen formulations has gained attention. Curcumin, an active compound found in turmeric (Curcuma longa) and Java turmeric (Curcuma xanthorrhiza), is well-known for its antioxidant and anti-inflammatory properties. This review explores the potential of curcumin as a natural ingredient for enhancing the Sun Protection Factor (SPF) of sunscreen products. A systematic literature review was conducted, analyzing 200 articles sourced from Google Scholar and PubMed using keywords such as “Curcumin”, “Curcuma”, “Antioxidant”, “Anti-Inflammatory”, and “Sun Protection Factor”. Studies unrelated to UV protection were excluded. The findings, presented in tabular form, indicate that curcumin and Curcuma exhibit significant potential to enhance SPF values due to their antioxidant, anti-inflammatory, and UV-absorbing properties. Additionally, curcumin may aid in skin repair following UV-induced damage. However, the specific concentration of curcumin in various Curcuma species remains unknown, and further research is necessary to determine its optimal use. Consideration of additional excipients in sunscreen formulations is also required to maximize efficacy. In conclusion, curcumin demonstrates considerable promise as a sustainable and effective natural ingredient for protecting the skin from UV radiation, offering a safer alternative to conventional chemical-based sunscreens.

Comparing Ultraviolet and Photocatalytic Disinfection Techniques and Their Synergistic Effects on Pesticide Presence and Quality Parameters in Grapes

ABSTRACTThe efficacy of ultraviolet (UV) and photocatalytic disinfection techniques, individually and synergistically, in degrading pesticide residues and maintaining quality parameters in grapes were investigated. A bench‐scale photocatalytic reactor equipped with UV lamps and photocatalysts (TiO₂ and ZnO) was used for the treatments. LC‐MS/MS was employed to check the presence and absence of pesticide residues after UV and photocatalyst treatments. UV‐C treatment alone showed an absence of chlorpyrifos and cyprodinil pesticides, whereas UV‐C with TiO₂ or ZnO led to near‐complete degradation of all pesticides found in grapes. Quality assessments showed a reduction in total phenolic content (TPC) from 269.4 ± 36.2 to 239.7 ± 30.2 mg GAE/100 g with UV‐C alone, whereas addition of TiO₂ improved TPC to 273.2 ± 18.3 mg GAE/100 g. Total flavonoid content (TFC) decreased significantly to 17.04 mg QE/100 g with UV‐C, but less so with UV‐B and UV‐A. Ascorbic acid content dropped from 34.91 to 15.75 mg/L with UV‐C, but UV‐B and UV‐A retained more ascorbic acid. Microbial analysis showed a reduction in total plate count from 6.30 ± 0.04 to 3.19 ± 0.10 log CFU/g with UV‐C. Overall, the combined treatments of photocatalysts assisted with UV demonstrated an environmentally friendly method for enhancing grape safety and quality, presenting a viable alternative for postharvest disinfection.

Deep learning reveals diverging effects of altitude on aging

Abstract Aging is influenced by a complex interplay of multifarious factors, including an individual’s genetics, environment, and lifestyle. Notably, high altitude may impact aging and age-related diseases through exposures such as hypoxia and ultraviolet (UV) radiation. To investigate this, we mined risk exposure data (summary exposure value), disease burden data (disability-adjusted life years (DALYs)), and death rates and life expectancy from the Global Health Data Exchange (GHDx) and National Data Management Center for Health of Ethiopia for each subnational region of Ethiopia, a country with considerable differences in the living altitude. We conducted a cross-sectional clinical trial involving 227 highland and 202 lowland dwellers from the Tigray region in Northern Ethiopia to gain a general insight into the biological aging at high altitudes. Notably, we observed significantly lower risk exposure rates and a reduced disease burden as well as increased life expectancy by lower mortality rates in higher-altitude regions of Ethiopia. When assessing biological aging using facial photographs, we found a faster rate of aging with increasing elevation, likely due to greater UV exposure. Conversely, analysis of nuclear morphologies of peripheral blood mononuclear cells (PBMCs) in blood smears with five different senescence predictors revealed a significant decrease in DNA damage-induced senescence in both monocytes and lymphocytes with increasing elevation. Overall, our findings suggest that disease and DNA damage-induced senescence decreases with altitude in agreement with the idea that oxidative stress may drive aging.

High-Aspect-Ratio Shape Replica Mold Fabrication Using Nanoimprinting and Silver Ink as Etching Mask

Effective high-aspect-ratio molds that minimize vacuum processes are becoming increasingly important for producing metalenses and other devices. To fabricate a high-aspect-ratio structure, a metal film must be used as a mask for dry etching, typically achieved via vacuum deposition. To avoid this vacuum process, we devised a method to develop an etching mask in the air using silver ink. The manufacturing method involved filling the mold with silver ink, baking it, removing silver from the convex parts of the mold with a polyethylene terephthalate film, and placing silver from the concave parts of the mold on top of the ultraviolet (UV)-cured resin using ultraviolet-nanoimprint lithography. The transferred pattern had silver on the convex parts, which was used as a mask for the oxygen dry etching of the UV-curable resin. Consequently, high-aspect-ratio resin shapes were obtained from three types of nano- and micromolds. Additionally, a high-aspect-ratio resin with silver was used as a replica mold to form a silver pattern. This process is effective and allows high-aspect-ratio patterns to be obtained from master molds.

Polycyclic aromatic hydrocarbon and the ultraviolet extinction bump at the cosmic dawn

First detected in 1965, the mysterious ultraviolet (UV) extinction bump at 2175Angstrom is the most prominent spectroscopic feature superimposed on the interstellar extinction curve. Its carrier has remained unidentified over the six decades since its first detection, although many candidate materials have been proposed. Widely seen in the interstellar medium of the Milky Way as well as several nearby galaxies, this bump was recently also detected by the James Webb Space Telescope (JWST) at the cosmic dawn in JADES-GS-z6-0, a distant galaxy at redshift z≈6.71, corresponding to a cosmic age of just 800 million years after the big bang. Differing from that of the known Galactic and extragalactic interstellar sightlines, which always peak at simali2175Angstrom, the bump seen at z≈6.71 peaks at an appreciably longer wavelength of simali2263Angstrom and is the narrowest among all known Galactic and extragalactic extinction bumps. Here we show that the combined electronic absorption spectra quantum chemically computed for a number of polycyclic aromatic hydrocarbon (PAH) molecules closely reproduce the bump detected by JWST in JADES-GS-z6-0. This suggests that PAH molecules had already been pervasive in the Universe at an epoch when asymptotic giant branch stars had not yet evolved to make dust.

Effects of Consuming Pulsed UV Light-Treated Pleurotus citrinopileatus on Vitamin D Nutritional Status in Healthy Adults

Vitamin D, essential for growth and health, is often deficient in Taiwan despite abundant sunlight. Plant-derived vitamin D2 (ergocalciferol) is bioavailable, environmentally friendly, and cost-effective. This study evaluated the efficacy of enhancing Pleurotus citrinopileatus (PC) mushrooms’ vitamin D2 content through pulsed ultraviolet (PUV) light and its impact on vitamin D status in humans. In a four-week randomized parallel trial, 36 healthy participants were assigned to three groups: a control group, a group consuming 10 g/day PUV-treated PC (PC-10 g), and a group consuming 100 g/day PUV-treated PC (PC-100 g). Blood samples collected pre- and post-intervention measured serum 25(OH)D2, 25(OH)D3, and biochemical parameters. After four weeks, serum 25(OH)D2 levels significantly increased in the PC-10 g group (1.47 ± 1.42 ng/mL to 9.50 ± 7.10 ng/mL, p = 0.001) and in the PC-100 g group (1.94 ± 2.15 ng/mL to 21.82 ± 16.75 ng/mL, p = 0.002), showing a 10.2-fold rise. The PC-100 g group also experienced a 37.6% reduction in serum intact parathyroid hormone (I-PTH) levels (26.26 ± 9.84 pg/mL to 16.38 ± 5.53 pg/mL). No adverse effects were reported. PUV-treated PC mushrooms significantly increase serum 25(OH)D2 levels and reduce I-PTH, particularly at higher doses. These findings underscore the potential of vitamin-D-enriched PC as a sustainable, fungi-derived food source for addressing vitamin D deficiency.

Ophthalmic oncology in awarmer world: climate-related increase in the prevalence of eyelid cancer

Damage induced by ultraviolet (UV) radiation plays adecisive role in the carcinogenesis of malignant tumors of the eyelids. Aselective literature search was performed in PubMed and Google Scholar. Large epidemiological studies show an increase in the prevalence of eyelid tumors in recent decades. The incidence of malignant eyelid tumors has increased especially in the white population over the last 70years. A UV-induced damage to tumor suppressor genes and oncogenes which play akey role in the carcinogenesis of malignant eyelid tumors has been demonstrated. Strong intermittent UV exposure and sunburn have been identified as risk factors for basal cell carcinoma and malignant melanoma. For squamous cell carcinoma, cumulative UV exposure over alonger period of time is considered arisk factor. In order to counteract the UV-related increase in malignant eyelid tumors, preventive protective measures, early detection and increased public awareness are essential. On the one hand, changes in behavior, appropriate clothing, wearing hats and sunglasses or contact lenses with UV filters are effective measures for UV protection. On the other hand, the underlying mechanisms of carcinogenesis should be investigated further in order to be able to carry out effective prevention and further develop treatment.

Clinicopathologic and Molecular Characterization of Basal Cell Carcinoma Arising at Sun-protected Sites.

Basal cell carcinomas (BCC) are driven primarily by cumulative ultraviolet (UV) radiation exposure resulting in activation of the Hedgehog (Hh) signaling pathway, often as a result of UV-mediated Patched-1 (PTCH1) gene inactivation. Accordingly, BCCs most commonly arise at sun-exposed sites such as the head and neck. Very rarely, BCCs can arise at sun-protected sites such as the genital skin and perianal area. This can pose significant diagnostic challenges not only due to the rarity of BCC at these sites but also due to the potential morphologic overlap with other entities such as basaloid squamous cell carcinoma, trichoblastic carcinoma, and even benign neoplasms such as trichoblastomas. Hh pathway alterations have not yet been described in BCCs arising at genital and perianal sites, and the role of UV radiation is uncertain at these anatomic locations. To address this ambiguity, we report the clinicopathologic features of a cohort of 14 BCCs arising at sun-protected sites (perianal n=7, vulva n=4, scrotum n=3). Furthermore, we use a next-generation DNA sequencing platform to investigate their pathogenesis and compare it to that of a cohort of 8 BCCs arising on sun-exposed skin. We find that BCCs arising on sun-protected sites display a spectrum of morphologic patterns, rarely recur, and do not metastasize. Both sun-protected and sun-exposed BCCs are characterized by recurrent PTCH1 alterations (93% and 100% of cases, respectively), supporting the classification of the tumors arising at sun-protected sites as bona fide BCCs. Notably, in contrast to conventional BCCs, none of the sun-protected BCCs harbored a UV mutation signature, suggesting an alternative mechanism of mutagenesis. Furthermore, the presence of upstream Hh pathway alterations in sun-protected BCCs supports their susceptibility to Hh pathway inhibitors such as vismodegib and sonidegib.

2D MoS2 for detection of COVID-19 biomarkers – a first-principles study

Abstract This study investigates specific compounds in the breath that can indicate COVID-19 and lung cancer. Heptanal (C7H14O), acetone (C3H6O), propanol-1 (CH3CH2CH2OH), butanal (C3H7CHO), isopropanol (CH3CHOHCH3), acetaldehyde (CH3CHO), 2,4-octadiene (C8H14), and ethyl butyrate (C6H12O2) were studied. We analyze how these compounds interact using two-dimensional (2D) 2H and SV-MoS2 monolayers through first-principles calculations. Van der Waals forces bind all VOCs on the MoS2 surface in vacuum and humid conditions. The decrease in the band gap of the MoS2-VOC complex in these environments enhances sensitivity. The complexes of 2,4-octadiene, propanol-1, and ethyl butanoate are more conductive because their work function is lower, and their V(z) shift is more significant. The adsorption isotherm demonstrates the potential for surface reuse in sensing applications. The study confirms high sensitivity (>85%) and fast recovery time (up to 70 femtoseconds) for detecting in visible (VL) and ultraviolet (UV) regions. Mainly, 2,4-octadiene exhibits high sensitivity and selectivity. In conclusion, the 2H and SV MoS2 monolayers effectively detect COVID-19 and lung cancer markers in vacuum and humid conditions.

Evaluation of Essential Oils as Natural Antibacterial Agents for Eggshell Sanitization and Quality Preservation

Eggs are considered a nutritionally complete food and an excellent source of protein. However, they are prone to bacterial contamination, which can affect their internal quality and safety. This study aimed to evaluate the effectiveness of essential oils (EOs) as natural sanitizers for eggshells to reduce the bacterial load and improve shelf life. Ten EOs—cinnamon, clove, lavender, peppermint, thyme, rosemary, green tea, mustard, basil, and marjoram—were tested for antibacterial activity against three Gram-positive bacteria (Staphylococcus aureus, Enterococcus faecalis, and Listeria monocytogenes) and three Gram-negative bacteria (Salmonella Enteritidis, Pseudomonas aeruginosa, and Escherichia coli) using the well diffusion method. The most effective EOs were assessed in vapor form using a disc volatilization technique. A total of 288 eggs from a local farm in South Lebanon were treated with selected EOs and stored at room temperature for three weeks to evaluate microbial load and quality. The eggs were grouped into six categories: dry control, ultraviolet (UV) treated, and eggs sprayed with EOs, based on the recorded minimum inhibitory concentration (MIC) values. At each time point, 12 eggs from each group were analyzed for microbiological testing and external and internal quality. Results indicated that nine of the ten EOs showed antibacterial activity, with the highest inhibition zones recorded for cinnamon against S. Enteritidis (14 mm) and E. coli (9 mm), peppermint against P. aeruginosa (10 mm), and rosemary against L. monocytogenes (22 mm), S. aureus (19 mm), and E. faecalis (12 mm). Vapor phase testing showed that rosemary, thyme, clove, and cinnamon EOs had average inhibition zones ranging from 21 to 33 mm against the tested bacteria, and peppermint EO achieved complete inhibition of P. aeruginosa. Clove EO consistently reduced the bacterial load as a sanitizer on eggs, initially achieving complete inhibition. While egg quality parameters such as weight, shell thickness, Haugh unit, and yolk color declined over time, EOs helped maintain better quality compared to dry controls. GC-MS analysis of the tested EOs revealed that monoterpene alcohols are the major constituents of most oils. This study concludes that EOs are effective natural sanitizers for eggs, enhancing safety and preserving quality during storage.

Ultra-stable transportable ultraviolet clock laser using cancellation between photo-thermal and photo-birefringence noise

Optical clocks require an ultra-stable laser to probe and precisely measure the frequency of the narrow-linewidth clock transition. We introduce a portable ultraviolet (UV) laser system for use in an aluminum quantum logic clock, demonstrating a fractional frequency instability of approximately mod σy = 2 × 10−16. The system is based on an ultra-stable cavity with crystalline AlGaAs/GaAs mirror coatings, with a frequency quadrupling system employing two single-pass second-harmonic generation (SHG) stages. Its acceleration sensitivity, measured in all three axes, does not exceed 4(2) × 10−12/(ms−2) and is among the lowest recorded for transportable systems to date. Additionally, partial cancellation between photo-thermal noise and photo-birefringence noise is used to effectively mitigate noise induced by intra-cavity optical power fluctuation at lower Fourier frequencies.

Acral Melanoma: A Review of Its Pathogenesis, Progression, and Management

Acral melanoma is a distinct subtype of cutaneous malignant melanoma that uniquely occurs on ultraviolet (UV)-shielded, glabrous skin of the palms, soles, and nail beds. While acral melanoma only accounts for 2–3% of all melanomas, it represents the most common subtype among darker-skinned, non-Caucasian individuals. Unlike other cutaneous melanomas, acral melanoma does not arise from UV radiation exposure and is accordingly associated with a relatively low tumor mutational burden. Recent advances in genomic, transcriptomic, and epigenomic sequencing have revealed genetic alterations unique to acral melanoma, including novel driver genes, high copy number variations, and complex chromosomal rearrangements. This review synthesizes the current knowledge on the clinical features, epidemiology, and treatment approaches for acral melanoma, with a focus on the genetic pathogenesis that gives rise to its unique tumor landscape. These findings highlight a need to deepen our genetic and molecular understanding to better target this challenging subtype of melanoma.

Many-body perturbation-theory calculation of electronic and optical properties of β-phase Be3N2

Abstract The hexagonal β-phase of bulk Be3N2 is a wide band gap semiconductor with potential ultraviolet (UV) optoelectronics applications. Here, we have performed the first theoretical study of the electronic and optical properties of the β phase of Be3N2 considering many-body effects. In particular, we have obtained the electronic band structure and spectra of the dielectric function, complex refractive index and electron energy loss function. For the calculation of the band structure, both Density Functional Theory and G0W0 approximation plus Wannier interpolation of the bands have been applied. For the calculation of the optical spectra, we have employed both the independent particle approach as well as the formalism that incorporates many-body and excitonic effects, by applying G0W0 approximation and solving the Bethe-Salpeter equation (BSE). The results show, for instance, that the spectrum of the imaginary part of the dielectric function of β-Be3N2 has an anisotropic behavior. Even more, the material shows its highest absorption peak in the UV range, which makes it interesting due to its possible high-temperature photodetection applications. Also, in the visible energy range of the spectrum, the index of refraction along the z-axis (see figure 1) is predicted to be around 1.6, which is a high value for a solid.

Design and Synthesis of Crystalline Al-Doped TiO2 Buffer Layers for Enhancing Energy Conversion Efficiency of New Photovoltaic Devices

Perovskite solar cells (PSCs) characterized by high energy conversion efficiency (ECE) and low manufacturing costs, exhibit promising potential for commercialization in the near term. For commercialization, it is very important to prevent the decomposition of perovskite by ultraviolet (UV) radiation in the air environment. Also, the mesoscopic architecture of PSCs presents considerable opportunities for the solar cell industry, offering potential for recycling of spent photocatalytic materials such as TiO2, and exploration of new energy resources. To solve these problems, therefore, this study introduces a strategy to mitigate these challenges using a crystalline Al-doped TiO2 buffer layer as the electron transport layer (ETL) in conjunction with a mesoporous TiO2 layer in the fabrication of PSCs. Among various Al concentrations in the crystalline Al-doped TiO2 buffer layer fabricated via spin-coating, an optimum concentration of 7 mol% Al yielded the highest cell performance in the specific perovskite solar cell structure. These solar cells exhibited an impressive ECE of 11.87%, representing a substantial enhancement of nearly double the ECE (6.37%) achieved with the conventional ETL. This remarkable improvement can be attributed to the passivation effect of the newly developed ETL, which combines a crystalline Al-doped TiO2 buffer layer with a mesoporousTiO2 layer. Electrochemical impedance spectroscopy (EIS) analysis was performed in conjunction with theoretical calculations of charge transport parameters to substantiate this claim.

Development of biocompatible mesoporous silica materials for enhanced UV protection

AbstractA new class of mesoporous silica (MPS)‐based biocompatible ultraviolet (UV) protective materials (1–4) has been prepared and characterized. These materials, which include avobenzone (AV)‐encapsulated MPS, were modified with biphenyl‐4‐triethoxysilane and polyethylene glycol (PEG200). Their photostability was tested under a sun‐simulated lamp. It was found that the structure of the material significantly impacts UV protection performance. Specifically, encapsulating AV‐enhanced UV radiation absorption, while the biphenyl layer improved UV‐blocking capabilities. Additionally, the PEG layer increased the materials' biocompatibility. Materials 1–4 demonstrated critical wavelengths of 389 nm and UV‐A/UV‐B ratios ranging from 0.61 to 0.89. Notably, the sun protection factor values were estimated between 6.04 and 17.24. In vivo testing on nude mice showed that untreated skin exhibited significant epidermal thickening due to sunburn. In contrast, skin treated with material 3 did not show any epidermal thickening, being 14 times thinner than unprotected skin. With high stability against photodegradation, materials 1–4 are promising candidates for UV protection applications, with material 3 proving to be the most effective.

Highly sensitive UV detector based on the transverse Dember effect of 4H-SiC single crystal

In this work, voltage-mode passive ultraviolet (UV) detectors have been designed and fabricated based on the transverse Dember effect of c-axis tilted n-type 4H-SiC single crystals, which may solve the disadvantages of traditional UV detectors with inadequate sensitivity and stability. A sensitivity as high as 96 000 μV/W has been identified in such 4H-SiC detectors via the transverse Dember effect under the illumination of UV light with a wavelength of 365 nm, which significantly exceeds those of traditional UV detectors based on the transverse thermoelectric effect. In addition, the rise time and decay time of 1.0 and 10.2 ms have been determined in these 4H-SiC detectors, respectively, which are much smaller than those of the current-mode detectors. These results may provide an approach to fabricate the high-performance UV detectors with low cost.

Application of Photolithography in Integrated Circuits

Integrated circuit (IC) manufacturing relies heavily on lithography, which drives device size reduction and performance improvement through precise pattern transfer. As the performance requirements of electronic devices continue to increase, lithography faces major challenges in terms of precision and efficiency. Currently, deep ultraviolet (DUV) and extreme ultraviolet (EUV) lithography technologies are mainstream, while technologies such as electron beam lithography (EBL) and directed self-assembly (DSA) are applied in specific high-precision fields. This paper reviews the current development status of lithography technology and analyzes its application in CMOS technology, 3D NAND flash memory, and high-performance computing components. The study also explores the main challenges facing photolithography, including technical bottlenecks, rising costs, and environmental impacts. In order to address these issues, the study emphasizes the importance of technological innovation and material improvement, especially in the development of new photoresists and mask materials and the promotion of environmentally friendly lithography technology. Therefore, it can be found that continued advances in lithography are essential to meet the changing needs of the semiconductor industry.