Tailoring of physical properties of RF-sputtered ZnTe films: role of substrate temperature

• Kafi Devi,
• Usha Rani,
• Arun Kumar,
• Divya Gupta and
• Sanjeev Aggarwal

Beilstein J. Nanotechnol. 2025, 16, 333–348, doi:10.3762/bjnano.16.25

• the optical bandgap of the films can be tuned from 1.47 ± 0.02 eV to 3.11 ± 0.14 eV. The surface morphology of the films studied using atomic force microscopy reveals that there is uniform grain growth on the surface. Various morphological parameters such as roughness, particle size, particle density

• , skewness, and kurtosis were determined. Current–voltage characteristics indicate that the conductivity of the films increased with substrate temperature. The observed variations in structural, morphological, and optical parameters have been discussed and correlated. The wide bandgap (3.11 eV), high

• crystallinity, high transmittance, and high conductivity of the ZnTe film produced at 600 °C make it a suitable candidate for use as a buffer layer in solar cell applications. Keywords: bandgap; physical properties; RF sputtering; substrate temperature; ZnTe; Introduction The industrialization and burning of

Emerging strategies in the sustainable removal of antibiotics using semiconductor-based photocatalysts

• Yunus Ahmed,
• Keya Rani Dutta,
• Parul Akhtar,
• Md. Arif Hossen,
• Md. Jahangir Alam,
• Obaid A. Alharbi,
• Hamad AlMohamadi and
• Abdul Wahab Mohammad

Beilstein J. Nanotechnol. 2025, 16, 264–285, doi:10.3762/bjnano.16.21

• bandgap, electrons (e−) in the valence band (VB) transition to the conduction band (CB), resulting in the formation of holes (h+) in the VB (photocatalyst + hν → photocatalyst + h+ + e−) [54][55]. Afterwards, the electrons and holes are effectively separated and move toward the surface of the

• (antibiotics + HO• and/or O2•− → CO2 + H2O). Mechanisms of metal, nonmetal, or co-doped photocatalysts The large bandgap and high electron–hole recombination rate of traditional and single semiconductor photocatalysts limit their effectiveness under visible light, which hinders their practical application. To

• CB of the material [58][59]. This action serves to reduce the bandgap, which in turn extends the absorption wavelength edge towards the region of visible light [60][61]. The idea of modifying semiconductor materials in the second generation involves the process of co-doping with both metal and

Recent advances in photothermal nanomaterials for ophthalmic applications

• Jiayuan Zhuang,
• Linhui Jia,
• Chenghao Li,
• Rui Yang,
• Jiapeng Wang,
• Wen-an Wang,
• Heng Zhou and
• Xiangxia Luo

Beilstein J. Nanotechnol. 2025, 16, 195–215, doi:10.3762/bjnano.16.16

• , and inorganic semiconductor materials that absorb light through bandgap transitions [25]. The specific photothermal properties of these materials, encompassing aspects such as range and rate of light absorption, photothermal conversion efficiency, heat transfer capability, and photothermal stability

• levels that fall between those of conductors and insulators. Their light absorption characteristics are primarily determined by their bandgap width, ranging from 0 to 3 eV (Figure 2g) [72]. Semiconductors with narrow bandgaps are capable of absorbing incident light energy that is greater than or equal to

• their bandgap energy (incident wavelength from approximately 310 to 1240 nm) [73], leading to the generation of electron–hole pairs that possess energy equivalent to the bandgap [74]. Once these excited electrons are transferred to impurities, defects, or surface dangling bonds [75], they release energy

Clays enhanced with niobium: potential in wastewater treatment and reuse as pigment with antibacterial activity

• Silvia Jaerger,
• Patricia Appelt,
• Mario Antônio Alves da Cunha,
• Fabián Ccahuana Ayma,
• Ricardo Schneider,
• Carla Bittencourt and
• Fauze Jacó Anaissi

Beilstein J. Nanotechnol. 2025, 16, 141–154, doi:10.3762/bjnano.16.13

• residues from the original organic matter, thus avoiding the disposal of sludge [8]. This approach allows the removal of various organic pollutants, including textile dyes, using solid semiconductors (e.g., NbOPO4 and Nb2O5) and photons (with energy greater than the bandgap energy of the semiconductor) to

• present profiles like BE clay, with intense absorption in the UV region with a sharp drop of around 550 nm [8]. This fact indicates the feasibility of activating the A-BEPh, A-BEPhP, A-BEOx, and A-BEOXPh samples under visible light (above 400 nm) [8]. The indirect bandgap energy values for the BE, NbOPO4

• and Nb2O5 and the bentonite clay modified with niobium BEPh and BEOx samples were estimated by the Tauc method [21]. For this, Kubelka–Munk method was applied as observed in Supporting Information File 1, Figure S2. The bandgap value of the BE sample (3.2 eV) was slightly higher than for the NbOPO4

TiO₂ immobilized on 2D mordenite: effect of hydrolysis conditions on structural, textural, and optical characteristics of the nanocomposites

• Marina G. Shelyapina,
• Rosario Isidro Yocupicio-Gaxiola,
• Gleb A. Valkovsky and
• Vitalii Petranovskii

Beilstein J. Nanotechnol. 2025, 16, 128–140, doi:10.3762/bjnano.16.12

• mesoporosity after calcination due to anatase nanoparticles of about 4 nm preventing the collapse of the interlamellar space. Immobilization of TiO2 on the zeolite surface is evidenced by the formation of Si–O–Ti bonds. The bandgap width of the synthetized nanocomposites was found to be sensitive to the

• efficiency than the bulk phase, but the bandgap of anatase particles smaller than 10 nm is very sensitive to their size [14]. One of the disadvantages of such free photocatalyst nanoparticles is the limitation of mass transfer between solid and liquid phases. From this perspective, the problem of

• the material. However, as it was shown in [44], the formation of a dense anatase phase has a strong influence on both the value of water adsorption energy and the distribution of water adsorption centers. UV–vis spectrometry To determine the bandgap energy Eg, the Tauc method was applied to the

Comparison of organic and inorganic hole transport layers in double perovskite material-based solar cell

• Deepika K and
• Arjun Singh

Beilstein J. Nanotechnol. 2025, 16, 119–127, doi:10.3762/bjnano.16.11

• , the double perovskite layer is sandwiched between the CTLs. In 2021, Kumar et al., reported a PCE of 9.68% for a La2NiMnO6 (LNMO)-based device structure after the bandgap had been optimized using the SCAPS-1D software [12]. In 2022, Porwal et al. reported a PCE of 23.64% with Cs2SnI6 as double

• the modeling of graded device structures up to seven layers and the computing of device parameters such as bandgap energy, efficiency, and J–V characteristics [19]. It helps in understanding the various functions of the device in more detail while indicating the aspects that have the highest impact on

• PEDOT:PSS are the two HTLs that are analyzed concerning the double perovskite material LNMO. The HTL needs better conductivity, better electron blocking, and more hole mobility for better carrier transportation at the perovskite/HTL interface. It is hydrophobic with a wider bandgap and does not easily

Characterization of ZnO nanoparticles synthesized using probiotic Lactiplantibacillus plantarum GP258

• Prashantkumar Siddappa Chakra,
• Aishwarya Banakar,
• Shriram Narayan Puranik,
• Vishwas Kaveeshwar,
• C. R. Ravikumar and
• Devaraja Gayathri

Beilstein J. Nanotechnol. 2025, 16, 78–89, doi:10.3762/bjnano.16.8

• ambient conditions with a bandgap and high exciton binding energy of 3.37 eV and −60 meV, respectively [10]. Because of this high exciton binding energy even at room temperature, the excitonic transitions have a broad range of applications such as in optics, gas detecting, piezoelectrics, and

• + cations. These findings offer information about the structure and chemical interactions within the ZnO NPs (Figure 2b). UV–vis absorption The UV–Vis absorption spectra of ZnO NPs, presented in Figure 2c, establish a distinct absorption peak at 3.16 eV, revealing the characteristic bandgap energy for ZnO

Instance maps as an organising concept for complex experimental workflows as demonstrated for (nano)material safety research

• Benjamin Punz,
• Maja Brajnik,
• Joh Dokler,
• Jaleesia D. Amos,
• Litty Johnson,
• Katie Reilly,
• Anastasios G. Papadiamantis,
• Amaia Green Etxabe,
• Lee Walker,
• Diego S. T. Martinez,
• Steffi Friedrichs,
• Klaus M. Weltring,
• Nazende Günday-Türeli,
• Claus Svendsen,
• Christine Ogilvie Hendren,
• Mark R. Wiesner,
• Martin Himly,
• Iseult Lynch and
• Thomas E. Exner

Beilstein J. Nanotechnol. 2025, 16, 57–77, doi:10.3762/bjnano.16.7

• nanomaterial properties, which can change as the surroundings change (such as zeta potential, which depends on the pH value and ionic strength of the surrounding medium [17]), and intrinsic nanomaterial properties, which are not affected by the surroundings (such as bandgap and structural arrangement) [18

Theoretical study of the electronic and optical properties of a composite formed by the zeolite NaA and a magnetite cluster

• Joel Antúnez-García,
• Roberto Núñez-González,
• Vitalii Petranovskii,
• H’Linh Hmok,
• Armando Reyes-Serrato,
• Fabian N. Murrieta-Rico,
• Mufei Xiao and
• Jonathan Zamora

Beilstein J. Nanotechnol. 2025, 16, 44–53, doi:10.3762/bjnano.16.5

• code employs the APW+lo method in conjunction with density functional theory (DFT) to calculate electronic structures. To determine the exchange–correlation interaction, we utilized the Tran–Blaha-modified Becke–Johnson (TB-mBJ) approximation. This approach provides calculated bandgap values that

• cluster reduces the bandgap and induces a shift in the band structure of the NaA zeolite toward negative energies, approximately by 1 eV. This observation is consistent with the results of prior research studies [61][62][63]. Figure 3c illustrates the band structure corresponding to the isolated magnetite

• bandgap of 6.5 eV, along with additional bandgaps originating from states associated with the bands at 4.5 and 5.2 eV. In Figure 4b, the TDOS for the NaA-M composite is presented, clearly revealing the decoupling of the spin-up and spin-down states, resulting in a “half-semiconductor”-type magnetic

Orientation-dependent photonic bandgaps in gold-dust weevil scales and their titania bioreplicates

• Norma Salvadores Farran,
• Limin Wang,
• Primoz Pirih and
• Bodo D. Wilts

Beilstein J. Nanotechnol. 2025, 16, 1–10, doi:10.3762/bjnano.16.1

• crystallites with different lattice orientations. The reciprocal space images and reflection spectra obtained from single domains indicated a partial photonic bandgap in the wavelength range from 450 to 650 nm. Light reflected from {111}-oriented domains is green-yellow. Light reflected from blue, {100

• replicas that exhibited a 70 to 120 nm redshift of the bandgap, depending on the lattice orientation. The wavelength shift in {100} orientation is supported by full-wave optical modeling of a dual diamond network with an exchanged fill fraction (0.56) of the material with the refractive index in the range

• particular, three-dimensional (3D) photonic crystals are characterized by a photonic bandgap that prohibits light of certain wavelengths from propagating through (specific) orientations of the material [3]. A complete photonic bandgap, where propagation of light waves in a certain wavelength band is

Fabrication of hafnium-based nanoparticles and nanostructures using picosecond laser ablation

• Abhishek Das,
• Mangababu Akkanaboina,
• Jagannath Rathod,
• R. Sai Prasad Goud,
• Kanaka Ravi Kumar,
• Raghu C. Reddy,
• Ratheesh Ravendran,
• Katia Vutova,
• S. V. S. Nageswara Rao and
• Venugopal Rao Soma

Beilstein J. Nanotechnol. 2024, 15, 1639–1653, doi:10.3762/bjnano.15.129

• [8] compared to bulk Hf. HfO2 is a wide-bandgap (5.68 eV) material with a high dielectric constant (≈25) [9][10]. HfC has a very high melting point (≈3900 °C) and ranks among the hardest materials, with a Vickers hardness value exceeding 20 GPa [4][11]. The properties vary substantially depending on

Heterogeneous reactions in a HFCVD reactor: simulation using a 2D model

• Xochitl Aleyda Morán Martínez,
• José Alberto Luna López,
• Zaira Jocelyn Hernández Simón,
• Gabriel Omar Mendoza Conde,
• José Álvaro David Hernández de Luz and
• Godofredo García Salgado

Beilstein J. Nanotechnol. 2024, 15, 1627–1638, doi:10.3762/bjnano.15.128

• ratio x = [O]/[Si], which is determined by controlling key parameters in the deposition process [2]. This ratio determines optical and electrical properties such as bandgap energy, absorption coefficient, photoluminescence, refractive index, and electrical conductivity [3]. SiOx cannot only be obtained

• comparison with that of oxygen, modifying stoichiometry and bandgap [35]. The distribution of H° in zone 2 is a result of the temperature distribution. The concentration is greater near the filaments, decreasing with distance along the y axis away from the quartz sources, where the temperature varies in the

Strain-induced bandgap engineering in 2D ψ-graphene materials: a first-principles study

• Kamal Kumar,
• Nora H. de Leeuw,
• Jost Adam and
• Abhishek Kumar Mishra

Beilstein J. Nanotechnol. 2024, 15, 1440–1452, doi:10.3762/bjnano.15.116

• applications. However, the metallic nature of these materials restricts their applications in specific domains. Strain engineering is a versatile technique to tailor the distribution of energy levels, including bandgap opening between the energy bands. ψ-Graphene is a newly predicted 2D nanosheet of carbon

• atoms arranged in 5,6,7-membered rings. The half and fully hydrogenated (hydrogen-functionalized) forms of ψ-graphene are called ψ-graphone and ψ-graphane. Like ψ-graphene, ψ-graphone has a zero bandgap, but ψ-graphane is a wide-bandgap semiconductor. In this study, we have applied in-plane and out-of

• -plane biaxial strain on pristine and hydrogenated ψ-graphene. We have obtained a bandgap opening (200 meV) in ψ-graphene at 14% in-plane strain, while ψ-graphone loses its zero-bandgap nature at very low values of applied strain (both +1% and −1%). In contrast, fully hydrogenated ψ-graphene remains

Lithium niobate on insulator: an emerging nanophotonic crystal for optimized light control

• Midhun Murali,
• Amit Banerjee and
• Tanmoy Basu

Beilstein J. Nanotechnol. 2024, 15, 1415–1426, doi:10.3762/bjnano.15.114

• , and spin–photon entanglement), and detection (involving single-photon detectors). Keywords: integrated photonics; lithium niobate; photonic bandgap; photonic crystal; titanium dioxide; Introduction One-dimensional photonic crystals (PhCs) are electromagnetic media in which materials are periodically

• arranged in a certain direction. The periodicity is proportional to the wavelength of light that lies in its photonic bandgap (PBG) [1]. The presence of the PBG and the potential ability to tune its position to match specific frequencies is perhaps the most attractive quality of PhC [2]. The specific

• in refractive index which is crucial for the creation of photonic bandgap [13]. In addition, these two materials are highly used in the photonics industry due to their easy availability and low cost. Moreover, both TiO2 and SiO2 can be integrated with various materials. The precise choice of

Various CVD-grown ZnO nanostructures for nanodevices and interdisciplinary applications

• The-Long Phan,
• Le Viet Cuong,
• Vu Dinh Lam and
• Ngoc Toan Dang

Beilstein J. Nanotechnol. 2024, 15, 1390–1399, doi:10.3762/bjnano.15.112

• comparison to other compounds [4][5][6]. Specifically, its large bandgap energy Eg ≈ 3.4 eV is comparable to GaN – a typical material for blue-light-emitting diode (LED) technology [7][8]. Also, its exciton binding energy is higher than the thermal energy at 300 K, and it has high-quality optical

Green synthesis of carbon dot structures from Rheum Ribes and Schottky diode fabrication

• Muhammed Taha Durmus and
• Ebru Bozkurt

Beilstein J. Nanotechnol. 2024, 15, 1369–1375, doi:10.3762/bjnano.15.110

• this diode were examined. The synthesized CDs are spherical with an average size of 5.5 nm, have a negative surface charge and contain 73.3 atom % C, 24.0 atom % O, and 2.7 atom % N. The CDs exhibit fluorescence at approximately 394 nm. The layer thickness and bandgap energy of the prepared CDs film

• the structure of the coated CDs film (Figure 5); the CDs film thickness was determined as ca. 566 nm. In addition, a UV–vis absorption spectrum of the CDs layer was taken (Figure 6a), and the bandgap value of the layer was determined from the graph of hν versus (αhν)2 using the Tauc equation [23]. The

• bandgap value of the CDs layer was 5.25 eV (Figure 6b). The current–voltage (I–V) characteristics of the Si/CDs/Au-based Schottky diode were investigated. I–V measurements of the CDs-based thin film device were carried out using a semiconductor parameter analyzer between −2.5 V and +2.5 V at room

Out-of-plane polarization induces a picosecond photoresponse in rhombohedral stacked bilayer WSe₂

• Guixian Liu,
• Yufan Wang,
• Zhoujuan Xu,
• Zhouxiaosong Zeng,
• Lanyu Huang,
• Cuihuan Ge and
• Xiao Wang

Beilstein J. Nanotechnol. 2024, 15, 1362–1368, doi:10.3762/bjnano.15.109

• lead to a high-efficiency photoelectric conversion that has the potential to surpasses the Shockley–Queisser limit [24][31][32][33][34]. In this regard, constructing 2D vdW semiconductors with OOP polarization and moderate bandgap holds great promise for high-performance self-powered BPVE devices. More

Mn-doped ZnO nanopowders prepared by sol–gel and microwave-assisted sol–gel methods and their photocatalytic properties

• Cristina Maria Vlăduț,
• Crina Anastasescu,
• Silviu Preda,
• Oana Catalina Mocioiu,
• Simona Petrescu,
• Jeanina Pandele-Cusu,
• Dana Culita,
• Veronica Bratan,
• Ioan Balint and
• Maria Zaharescu

Beilstein J. Nanotechnol. 2024, 15, 1283–1296, doi:10.3762/bjnano.15.104

• catalyst bandgap and its surface chemistry relative to reactant adsorption and photocatalytic activity were also clearly shown [56]. According to the abovementioned data, the possible routes for the present photocatalytic process can be described as follows: The main question to be answered is which of

• determined using the Tauc plot method, considering direct transitions. The method consists in the extrapolation of the linear region of the rising part of the curve (αhν)1/η as a function of hν to zero to get the bandgap (where α is the Kubelka–Munk function, hν is the energy of the photons, and η has the

• value 1/2 for direct-bandgap semiconductors and 2 for indirect-bandgap semiconductors or amorphous compounds. Photoluminescence measurements (PL) were carried out using a Carry Eclipse fluorescence spectrometer from Agilent Technologies and the following parameters: scan rate of 120 nm·min−1, spectral

Quantum-to-classical modeling of monolayer Ge₂Se₂ and its application in photovoltaic devices

• Anup Shrivastava,
• Shivani Saini,
• Dolly Kumari,
• Sanjai Singh and
• Jost Adam

Beilstein J. Nanotechnol. 2024, 15, 1153–1169, doi:10.3762/bjnano.15.94

• –k dispersion reveals the investigated material’s key electronic properties. The calculations reveal a direct bandgap of 1.12 eV for monolayer Ge2Se2. We further extract critical optical parameters using the Kubo–Greenwood formalism and Kramers–Kronig relations. A significantly large absorption

• extensive applications in photodevices. This is mainly because of the exceptional optoelectronic behavior of the TMDCs, especially the layer-dependent bandgap and the high absorption of incident sunlight [22][23][24][25]. Motivated by this, various TMDCs, including MoS2, WS2, WSe2, and TiS2, have been used

• . Figure 3 depicts that the monolayer Ge2Se2 is a direct-bandgap semiconductor with a bandgap of the order of 1.12 eV. Valence band maximum (VBM) and conduction band minimum (CBM) are located along the Γ-X path. The computed bandgap value and its dispersion nature are consistent with earlier reported works

Photocatalytic methane oxidation over a TiO₂/SiNWs p–n junction catalyst at room temperature

• Qui Thanh Hoai Ta,
• Luan Minh Nguyen,
• Ngoc Hoi Nguyen,
• Phan Khanh Thinh Nguyen and
• Dai Hai Nguyen

Beilstein J. Nanotechnol. 2024, 15, 1132–1141, doi:10.3762/bjnano.15.92

• because of its high stability, good dispersibility, and narrow energy bandgap. However, pristine TiO2 shows only low photocatalytic efficiency because of the high recombination rate between holes and electrons and the low visible-light harvesting ability [20][21][22]. The rapid recombination of charge

• electron–hole pairs. Additionally, TiO2/SiNWs offer flexibility, improved bandgap energy, and enhanced light harvesting across a broad spectrum, leading to higher photocatalytic efficiency. Combining SiNWs and TiO2 presents an opportunity to leverage the strengths of both materials while mitigating their

• TiO2/SiNWs catalyst may be attributed to the vertical wires, which enable strong light scattering leading to enhancement in light harvesting. The optical bandgap values of SiNWs and TiO2/SiNWs are estimated at around 3.8 and 3.3 eV, respectively. Figure 3b displays the current–voltage (I–V) curves of

Local work function on graphene nanoribbons

• Daniel Rothhardt,
• Amina Kimouche,
• Tillmann Klamroth and
• Regina Hoffmann-Vogel

Beilstein J. Nanotechnol. 2024, 15, 1125–1131, doi:10.3762/bjnano.15.91

• bandgap [12], which is also related to the work function. GNRs can be synthesized with atomic precision in an ultrahigh-vacuum environment using on-surface synthesis [13]. This synthesis is well known on coinage metals, namely, Cu, Ag, and Au, which possess a high electron density. To study these unique

Interface properties of nanostructured carbon-coated biological implants: an overview

• Mattia Bartoli,
• Francesca Cardano,
• Erik Piatti,
• Stefania Lettieri,
• Andrea Fin and
• Alberto Tagliaferro

Beilstein J. Nanotechnol. 2024, 15, 1041–1053, doi:10.3762/bjnano.15.85

• quantum confinement as reported by Bolker and co-workers [77]. Authors reported that the bandgap of NDs is strongly correlated to the NDs’ size, and it increases with decreasing crystallite size. However, the ND properties can be altered by heteroatomic doping and through the introduction of surface

Recent progress on field-effect transistor-based biosensors: device perspective

• Billel Smaani,
• Fares Nafa,
• Mohamed Salah Benlatrech,
• Ismahan Mahdi,
• Hamza Akroum,
• Mohamed walid Azizi,
• Khaled Harrar and
• Sayan Kanungo

Beilstein J. Nanotechnol. 2024, 15, 977–994, doi:10.3762/bjnano.15.80

• of the electrode gate (with metal 2) is interfaced with HfO2 high-k dielectric with the body channel. The source region is P+ doped but the drain region is N+ doped, as shown in Figure 17. In this context, a low bandgap material (InAs) was implemented in the source region to achieve better band-to

• to other TFET-based biosensor topologies [126][127] and conventional FET-based biosensors [128] by utilizing a gate-engineered heterostructure and low bandgap materials in the source region, which facilitates efficient carrier band-to-band tunneling. Furthermore, extended gate architecture is

Intermixing of MoS₂ and WS₂ photocatalysts toward methylene blue photodegradation

• Maryam Al Qaydi,
• Nitul S. Rajput,
• Michael Lejeune,
• Abdellatif Bouchalkha,
• Mimoun El Marssi,
• Steevy Cordette,
• Chaouki Kasmi and
• Mustapha Jouiad

Beilstein J. Nanotechnol. 2024, 15, 817–829, doi:10.3762/bjnano.15.68

• ]. Typically, semiconductor-based photocatalysts, such as TiO2, ZnO2, and some other high-bandgap transition-metal dichalcogenides (TMD) have shown their ability to efficiently degrade the activated MB by irradiation [10][11]. Recently, TMD such as MoS2 and WS2, have displayed remarkable potential as

• adsorbed onto the surface of the catalyst [20], then the illumination with energy greater than that of the bandgap will promote electrons (e−) to the conduction band (CB), leaving holes (h+) in the valence band (VB). Simultaneously, oxygen molecules on the surface of the catalyst capture the excited

• materials while taking into account their bandgap energies, as per the following equations: where ECB is the energy level of the conduction band, EVB is the energy level of the valence band, Eg(x) and X(x) are the bandgap and the electronegativity of the respective material. E0 represents the scaling

Effect of repeating hydrothermal growth processes and rapid thermal annealing on CuO thin film properties

• Monika Ozga,
• Eunika Zielony,
• Aleksandra Wierzbicka,
• Anna Wolska,
• Marcin Klepka,
• Marek Godlewski,
• Bogdan J. Kowalski and
• Bartłomiej S. Witkowski

Beilstein J. Nanotechnol. 2024, 15, 743–754, doi:10.3762/bjnano.15.62

• devices. Keywords: CuO; hydrothermal method; rapid thermal annealing; thin films; Introduction Copper(II) oxide is a p-type semiconductor possessing a narrow bandgap, along with many beneficial electrical, optical, and magnetic properties. Particularly at the nanoscale, these properties set themselves