N-type Behavior Research Articles

Effects of forming gas annealing on the doping of monolayer MoS2 crystals

Here we report the effects of forming gas (5% H2 in N2) annealing on the doping behavior of mechanically-exfoliated, natural n-type MoS2 monolayers. Although the fabricated MoS2 transistors exhibited an enhanced device performance because of the reduced contact resistance after annealing at 200 °C for 2 h, the corresponding Raman and photoluminescence spectra suggested that the forming gas annealing suppressed the n-type doping behavior of MoS2. X-ray photoelectron spectroscopy and Kelvin probe force microscopy measurements consistently suggested a downward movement of the Fermi level of the MoS2 monolayers after the forming gas annealing. These results demonstrate the importance of optimizing the process conditions during the forming gas annealing for the fabrication of MoS2 transistors and devices based on transition metal dichalcogenides.

Demonstration and analysis of ambipolar SnO inverter with high gain

Ambipolar materials offer a unique and simple route toward cost-effective complementary thin film circuits. SnO is one of the few metal oxide semiconductors that demonstrates ambipolar behavior. In this work, we demonstrated an ambipolar SnO inverter with record high inverter gain and corroborated our experimental results with a comprehensive analytical model. First, we developed ambipolar SnO thin film transistors (TFTs) with symmetric p-type and n-type conduction. Using these ambipolar SnO TFTs, we fabricated ambipolar SnO inverters. Our ambipolar SnO inverter shows a record gain of 432 (V/V), which is the highest reported among all ambipolar material systems. To understand our high inverter gain, we developed a comprehensive analytical model to analyze the transition region of an ambipolar inverter. Our analytical model showed an excellent match with our experiment results. Furthermore, our analytical model shows that to achieve a high inverter gain and a voltage transition point in the middle of the supply voltage range, we must minimize channel length modulation and match the p- and n-type behaviors of the ambipolar TFTs. By expanding our understanding of ambipolar inverter behavior, this work highlights the possibilities of ambipolar SnO TFTs for future high performance complementary thin film circuits.

Investigation of the electronic structure, mechanical, and thermoelectric properties of novel semiconductor compounds: XYTe (X = Ti/Sc; Y = Fe/Co).

We report the structural, mechanical, electronic, phonon, and thermoelectric properties of new XYTe (X= Ti/Sc; Y = Fe/Co) half-Heusler compounds by employing first principles based DFT computation and Boltzmann transport equations. At their equilibrium lattice constants, these alloys exhibit a crystal structure with a space group (#216) of F4̄3m and adhere to the Slater Pauling (SP) rule, while being non-magnetic semiconductors. The Pugh's ratio of TiFeTe shows that it is a ductile material, which makes it suitable for use in thermoelectric applications. On the other hand, ScCoTe's brittleness or fragility makes it less promising as a potential thermoelectric material. The dynamical stability of the system is investigated using the phonon dispersion curves obtained from its lattice vibrations. The band gaps of TiFeTe and ScCoTe are 0.93 eV and 0.88 eV, respectively. The electrical conductivity (σ), Seebeck coefficient (S), thermoelectric power factor (PF), and electronic thermal conductivity are calculated at various temperatures ranging from 300 K to 1200 K. At 300 K, TiFeTe has a Seebeck coefficient of 1.9 mV K-1 and a power factor of 136.1 mW m-1 K-2. The highest S value for this material is obtained through n-type doping. The optimal carrier concentration for achieving the highest Seebeck coefficient in TiFeTe is 0.2 × 1020 cm-3. Our study indicates that the XYTe Heusler compounds exhibit n-type semiconductor behavior.

A Multifunctional "halide-Equivalent" Anion Enabling Efficient CsPb(Br/I)3 Nanocrystals Pure-Red Light-Emitting Diodes with External Quantum Efficiency Exceeding 23.

All-inorganic perovskite nanocrystals (NCs) are promising candidates for light-emitting diodes (LEDs) owing to their excellent optoelectronic properties. However, the pure-red perovskite LEDs (PeLEDs) available today made from mixed-halide CsPb(Br/I)3 NCs suffer from a compromise in their emission efficiency and spectral stability on account of severe trap-mediated nonradiative recombination loss, halide phase segregation, and self-doping effect, all of which are caused by the surface halide vacancies. Herein, we introduced a "halide-equivalent" anion of benzenesulfonate (BS- ) into CsPb(Br/I)3 NCs as multifunctional additive to simultaneously address the above challenging issues. Joint experiment-theory characterizations reveal that the BS- can not only passivate the uncoordinated Pb2+ related defects at surface of NCs, but also increase the formation energy of halide vacancies, resulting in substantially improved optical properties and phase stability of NCs. Moreover, electrons are expected to transfer from the CsPb(Br/I)3 NC to BS- because of the strong electron-withdrawing property of sulfonate group, which reduces the self-doping effect and alters the n-type behavior of CsPb(Br/I)3 NCs to near ambipolarity for balancing carrier injection in the device. Eventually, synergistic boost in device performance is achieved for pure-red PeLEDs with Commission Internationale del'Eclairage color coordinates of (0.70, 0.30) and a champion external quantum efficiency of 23.5%, which is a record value among the ever-reported red PeLEDs approaching to the Rec. 2020 red primary color. Moreover, the BS- -modified PeLEDs demonstrates robust spectral stability, showing negligible wavelength shift under different operating voltages. This strategy paves an efficient way for improving the efficiency and stability of pure-red PeLEDs. This article is protected by copyright. All rights reserved.

Pseudobrookite (Fe2TiO5) films: Synthesis, properties and photoelectrochemical characterization

Pseudobrookite, Fe2TiO5, precursor films were obtained by spray pyrolysis (SP) at 550 °C on fused silica and FTO (F-doped tin oxide on borosilicate glass) using iron (III) acetylacetonate (FeAcAc) and titanium diisopropoxide bis(acetylacetonate) (DIPTiAcAc) in methanol. SP was followed by annealing in air from 600 °C to 1000 °C for various durations, and for T ≥ 750 °C, phase pure pseudobrookite was obtained. (Photo)electrochemical experiments of Fe2TiO5 electrodes in junctions with aqueous electrolytes showed n-type behaviour of the material with a maximum photocurrent of 0.35 mA/cm2 under simulated AM1.5 sunlight. A valence band energy between 6.6 and 6.8 eV was estimated using the electrochemical results. The position of the Fe2TiO5 valence band enables the passage of (photogenerated) holes in hematite into a pseudobrookite layer and further on towards an electrolyte, if a hematite/pseudobrookite stratified film would be applied in a solid / liquid junction. The valence band potential is not positive enough for producing OH· radicals, only solvent oxidation and reactions which do not require OH· radicals can proceed.

Tunable electrical contacts in two-dimensional silicon field-effect transistors: The significance of surface engineering

Two-dimensional silicon (2D-Si) semiconductor is highly desired for future field-effect transistors (FETs) due to the inherent compatibility with the silicon-based technology. Interfacial contact represents a significant bottleneck restricting the performance of 2D-Si-based FETs. Here, by first-principles calculations and quantum transport simulations, we propose a strategy of surface engineering by F-, H-, and OH-passivation to tune the electronic properties, electrical contacts, and device performance of 2D FETs based on monolayer dumbbell silicene (LHD-Si). It is found that surface passivation performed in the LHD-Si FETs can significantly eliminate the metal-induced gap states and greatly relieve the Fermi level pinning by improving the pinning factor from 0.08 to 0.46. Importantly, the LHD-Si monolayers passivated with F and OH prefer to form n-type and p-type contacts with the representative metals (Bi, Al, Ag, Cu, Au, and Pt), respectively. Among them, Ohmic or quasi-Ohmic contacts (with very small Schottky barrier) are realized for F-passivated (OH-passivated) LHD-Si with Bi/Al/Ag (Cu/Au/Pt) electrodes. In the particular case of LHD-Si FETs with Cu electrodes, n-type, p-type, and ambipolar-type transfer behaviors are obtained for the F-, OH–, and H-passivation, respectively, demonstrating the dominant role played by electrical contacts in determining the Schottky barrier of the devices. This work highlights the significance of surface engineering in tuning the electrical contact and transport properties of doping-free 2D-Si-based FETs.

Probing Intrinsic Defect-Induced Trap States and Hopping Transport in Two-Dimensional PdSe2 Semiconductor Devices.

Palladium diselenide (PdSe2), as an emerging two-dimensional (2D) layered material, is gaining growing attention in nanoelectronics and optoelectronics due to its thickness-dependent band gap, high carrier mobility, and good air stability. However, its asymmetric pentagon structure is inclined to breed defects. Herein, the intrinsic Se vacancy-induced trap states and their influence on the hopping transport in PdSe2 are systematically investigated. We provide direct evidence that Se vacancies exist in the fresh PdSe2 samples, which results in the localized trapping states inside the band gap. For the few-layer PdSe2, at 77 K, the trap density (Dit) near the midgap is about 2.2 × 1013 cm-2 eV-1, whereas at 295 K, the Dit value increases to ∼7.1 × 1013 cm-2 eV-1. By comparison, the multilayer PdSe2 shows nonobvious temperature-dependent trap behaviors with almost unchanged Dit values of ∼8.1 × 1012 cm-2 eV-1 at midgap in the temperature range between 77 and 295 K. Thus, trap states in the few-layer PdSe2 are more vulnerable to temperature effect. Transport measurements demonstrated that both few-layer and multilayer PdSe2 field-effect transistor (FET) devices show n-type dominant ambipolar behaviors. The electron mobility in the multilayer PdSe2 FET is nearly 15-fold higher than that in the few-layer PdSe2 FET at 315 K, probably owing to the decreased effective mass and suppression of charge impurity scattering in the thicker channel material. However, both FET devices exhibit variable-range hopping over a temperature range from 77 to 240 K and thermally activated hopping at temperatures above 240 K. The hopping transport mechanism is strongly associated with the Se vacancy-induced localized states with poor screening and strong potential fluctuations. This study reveals the important role of structural defects in tailoring and improving the charge transport properties of PdSe2.

Controllable growth of wafer-scale monolayer transition metal dichalcogenides ternary alloys with tunable band gap

The tuning of band gap is very important for the application of two-dimensional (2D) materials in optoelectronic devices. Alloying of 2D transition metal dichalcogenides (TMDCs) is an important way to tune the wide band gap. In this study, we report a multi-step vapor deposition method to grow monolayer TMDC ternary alloy films with wafer scale, including Mo1−x W x S2, Mo1−x W x Se2 and MoS2x Se2(1−x), which are accurately controllable in the elemental proportion (x is from 0 to 1). The band gap of the three 2D ternary alloy materials are continuously tuned for the whole range of metal and chalcogen compositions. The metal compositions are controlled by the as-deposited thickness. Raman, photoluminescence, elemental maps and TEM show the high spatial homogeneity in the compositions and optical properties across the whole wafer. The band gap can be continuously tuned from 1.86 to 1.99 eV for Mo1−x W x S2, 1.56 to 1.65 eV for Mo1−x W x Se2, 1.56 to 1.86 eV for MoS2x Se2(1−x). Electrical transport measurements indicate that Mo1−x W x S2 and MoS2x Se2(1−x) monolayers show n-type semiconductor behaviors, and the carrier types of Mo1−x W x Se2 can be tuned as n-type, bipolar and p-type. Moreover, this control process can be easily generalized to other 2D alloy films, even to quaternary or multi-element alloy materials. Our study presents a promising route for the preparation of large-scale homogeneous monolayer TMDC alloys and the application for future functional devices.

Fast-Response Amorphous In2Te3 Short-Wave Infrared (SWIR) Photodetector

Despite the wide applications of Short-Wave Infrared (SWIR) imaging, standard imaging materials require lattice matching and complex fabrication techniques which are relatively expensive. In this work, 50 nm thick amorphous indium telluride (In2Te3) films are RF sputtered on a silicon (Si/SiO2) substrate at 300 °C. The films are used to fabricate back-gated field-effect photodetectors (PDs). The In2Te3 detectors exhibit a broad wavelength response from 406 nm to 1600 nm and a photo responsivity of 0.44 AW− under 1310 nm excitation at 5 V bias. Furthermore, an n-type behavior with an electron field-effect mobility of 1.15 cm2V−1s−1 is observed. We also evaluated the frequency response of the PDs under 1310 nm modulated light, a 3dB cut-off frequency of ~0.97 MHz is measured. Further, the device exhibits specific detectivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.32\times 10^{{9}}$ </tex-math></inline-formula> Jones and very good stability at ambient conditions.

Hydrothermally modified ZnO-NiSe heterostructure as promising photoelectrocatalyst in hydrogen evolution reaction

Water splitting through electrolysis is the standard and efficient method to generate hydrogen on a large scale. The efficiency of this method can be increased using the photoelectrochemical technique by using an effective photoelectrocatalyst. This work demonstrates ZnO-NiSe@NF as a potential photoelectrocatalyst for hydrogen evolution reactions (HER). The heterostructure is synthesized by hydrothermal method, and the electrochemical and photoelectrochemical analyses are done in an acidic medium using a 0.5 M H2SO4 solution. In electrochemical measurements, ZnO-NiSe@NF shows excellent performance with a lower overpotential (-0.081 V) and low Tafel slope of 80.01 mV/dec. The photoelectrochemical linear sweep voltammetry measurements show an enhancement in HER performance, with the positive shift of overpotential to −0.065 V. Mott-Schottky analysis demonstrates n-type behavior for the composite where the electrons are the primary charge carrier. The possible mechanism of the reaction has been discussed.

Thickness dependent wavelength selective NIR-UV-visible photoresponse in ZnO nanowires and silicon heterojunction

In this paper, we report ZnO nanowires (NWs) and silicon-based type-II PN heterojunction for UV–Visible–Infrared self-powered photodetection. The as-grown ZnO NWs were highly crystalline and aligned along the c-axis in the [002] direction revealed in the HRTEM and XRD measurements. The Hall measurements revealed the n-type behavior for ZnO and p-type for p-Si with carrier concentrations of 4.09 × 1016 cm−3 and 1.38 × 1017 cm−3, respectively. The depletion widths were estimated to be ∼35 nm and ∼120 nm, respectively for p-Si and n-ZnO NWs. The Ag/n-ZnO NWs/p-Si/Ag PN heterojunction showed large photoresponse, even at zero bias, under the illumination of commercially available UV–Visible–NIR LEDs, thus acting as a self-powered photodetector. It was interesting to observe that the photoresponse was dependent on the growth time and hence the thickness of ZnO NWs thin film. A maximum zero bias responsivity of ∼0.1 A/W at green (515 nm) was observed and was large for the junction with thicker ZnO NWs film (5 h growth), compared with thinner (3 h growth) device under IR (950 nm) LED illumination, however, it was observed otherwise for UV (395 nm) LED. This suggests that tuning the thickness of the ZnO NWs thin film results in the wavelength selective photoresponse, consequently, paving the way towards UV blind IR-visible photodetector based on ZnO NWs. The transient short circuit current (Isc vs t) and open circuit voltage (Voc vs t) properties showed fast and large responses under periodic illumination of all LEDs (UV–Vis–NIR). The response was observed to depend on the intensity of light and the maximum Voc comes out to be ∼102 mV and Isc ∼5.58 μA, under the illumination of a red laser diode.

Naphthodipyrrolopyrrole-based Aza-BODIPY dye for N-type organic field-effect transistors

To date, n-type semiconductor designs are less investigated than their p-type counterparts, due to the fact that the charge transport mobility and the stability of the n-type materials are generally lower than those of the p-type ones. Well-defined n-type semiconductors often require low lowest unoccupied molecular orbital (LUMO) levels that facilitate the electron injection from the electrode into the semiconductors. Therefore, it is of significance to explore novel chromophores with strong electron-deficient properties, yet it is still challenging. Herein, a naphthodipyrrolopyrrole-based dimeric aza-boron dipyrromethene (Aza-BODIPY) dye (NDP-AB) is designed and synthesized. The optical studies indicate that NDP-AB presents a blue spectral shift (111 nm) in solution phase compared to the thin film state, while exhibiting a photoluminescence emission quenching. The NDP-AB semiconductor demonstrates strong acceptor properties with a low LUMO energy level of only −4.25 eV, owing to the multi-fluorine atoms, unsaturated nitrogen atoms, as well as the amide functional groups. Moreover, the large conjugation system, highly planar core, along with the large transition dipole on the line that links 2-position with 6-position of the BODIPY core, result in NDP-AB with a strong H-aggregation. As a consequence, the NDP-AB-based semiconductors show a good n-type behavior with an average electron mobility of 0.16 cm2 V−1 s−1. Our work, proposes a strong electron-deficient chromophore that is a promising candidate as building block of organic field-effect transistors. Our design strategy paves the way for the identification of more n-type semiconductor materials with high-performance.

Origin of contact polarity at metal-2D transition metal dichalcogenide interfaces

Using state-of-the-art ab initio GW many-body perturbation theory calculations, we show that monolayer MoS2 on Au is a p-type contact, in contrast to the vast majority of theoretical predictions using density functional theory. The predominantly n-type behaviour observed experimentally for MoS2/Au junctions can be attributed to the presence of sulfur vacancies, which pin the Fermi level. GW calculations on WSe2/Au junctions likewise predict p-type contacts for pristine WSe2 and n-type contacts for junctions with selenium vacancies. Experimentally, WSe2/metal junctions are predominantly p-type or ambipolar, with p-type junctions being observed for selenium-deficient WSe2, suggesting that selenium vacancies are not effective in pinning the Fermi level for WSe2/metal junctions. We rationalize these apparently contradictory results by noting that selenium vacancies in WSe2 are readily passivated by oxygen atoms. Taken together, our state-of-the-art calculations clearly elucidate the relation between contact polarity and atomic structure. We show that non-local exchange and correlation effects are critical for determining the energy level alignment and even the contact polarity (in the case of MoS2 on Au). We further reconcile a large body of experimental literature on TMDC/metal contact polarities by consideration of the defect chemistry.

ZnO-doped PFPAMA: a novel transparent conducting polymer for fast photodiodes

In this article, a new Schottky diode based on a transparent conducting polymer 2-(4-fluorophenyl)-2-oxoethyl-2-methylprop-2-enoate (PFPAMA) that is doped up to 5% with ZnO is presented. PFPAMA is a promising transparent polymer that is inclined towards n-type behavior with the potential to be used as an electron transport layer. Each device had the Al/p-Si:(PFPAMA:ZnO)/Al structure. The diode ideality factor was found to depend on bias and illumination but the calculated interface state density is lower by 3 orders of magnitude than for most reported Al/p-Si diodes, suggesting that the presence of the polymer suppresses interface states. The measured electrical and photoresponse characteristics confirm that the resulting diodes are suitable for fast photodiodes over the intensity range of dark to 100 mW/cm2 whose performance can be optimized by ZnO doping. The application of functionalized polymers on p-silicon for sensing applications is an emerging field.

Electrical Transport Properties of Few-Layer SnS2 Field-effect Transistors

After the discovery of graphene in 2004, two dimensional (2D) materials have fascinated a lot of view due to the excellent properties. Nowadays, the research on 2D materials has spread to other graphene-like layer structured materials, especially transition metal dichalcogenides (TMDCs). Tin disulfide (SnS2) is a kind of TMDCs with a sizable bandgap. Here we introduce few-layer SnS2 field-effect transistors (FETs) fabricated using micromechanical exfoliation method. The FETs show n-type behavior, the on/off ratio exceeding 0.54×104 and the carrier mobility is 0.61 cm2V−1s−1. The electronic and optical characteristics of SnS2 flakes with a finite bandgap illustrate their potential applications in optoelectronics device.

Isoindigo-based aza-BODIPY small molecule for N-type organic field-effect transistors

To date, most of the reported conjugated materials are p-type semiconductors, while the advances in n-type or ambipolar conjugated materials greatly fall behind those in p-type counterparts. Well-defined n-type semiconductors should possess suitable electron-deficient groups and relatively low lowest unoccupied molecular orbitals (LUMO) levels that facilitate the electron injection and stabilize the electron transport. Thus, developing novel n-type semiconductor materials with strong electron-deficient property, high electron mobility, and competitive stability is still highly desirable, though challenging. Herein, a new isoindigo-based dimeric aza-boron dipyrromethene (aza-BODIPY) chromophore (IIDG-AB) is designed and synthesized. IIDG-AB contains multiple fluorine and unsaturated nitrogen atoms, which endow it with strong electron-deficient property as well as an ultra-low LUMO level of only −4.24 eV. In addition, IIDG-AB features a large conjugation system and a high degree of coplanarity, which are beneficial for effective intermolecular charge transfer. The UV/visible absorption spectra, X-ray diffraction analysis, and morphological studies via atomic force microscopy imaging indicate that the IIDG-AB thin film presents strong aggregation, good π-π stacking, and long-range order packing, all of which are favorable for the electron transfer between neighboring molecules. Furthermore, IIDG-AB-based organic field-effect transistors exhibit a moderate stable n-type behavior with the highest electron mobility of 1.1 × 10−1 cm2 V−1 s−1. This work provides a simple and effective strategy to synthesize highly functional n-type chromophores via a Schiff base reaction between bislactams and heteroaromatic amines, and also paves the way for future design to fabricate high-performance n-type semiconductor materials for a wide range of applications.

Effect of Ni toward the optical and transport properties of the spinel solid solution NixCu1−xFe2O4 nanoparticles

The solid solution NixCu1−xFe2O4 (x = 0, x = 0. 2,….x = 1) crystallizing in the spinel structure were prepared by the Sol-Gel method at 800 °C. The novelty of the work is also devoted to the synthesis of the spinel ferrites NixCu1−xFe2O4 (0 < x < 1) using the sol gel technique and the measurement of their structural and magnetic properties by X-ray diffraction and magnetic measurements. The structural, magnetic, optical and electrical properties were investigated. The formation of the tetragonal phase with a good crystallization and stoichiometric contents were confirmed by X-ray diffraction (x = 0 and 0.2) while a transition to cubic symmetry is observed for the other compositions. NixCu1−xFe2O4 exhibits n-type conduction with an increased band gap (Eg) as Ni is introduced in the crystal lattice while it decreases with augmenting the Ni-content in the cubic phase. The transport properties are characteristic of n-type behavior where the electrical conductivity decreases up to x = 0.4. Then, it increases and the conduction is mainly governed by the thermal emission over the inter-crystallites. An average hole mobility of ∼ 10−5 cm2 V−1 s−1 was determined for both symmetries. Magnetic measurements revealed that the saturation magnetization (Ms) increases with the Ni-content whereas the coercivity decreases. NiFe2O4 has the largest saturation magnetization (38.16 emu/g). The optical properties namely the energy gap (Eg), reflection index (n), extinction coefficient (k), dielectric complex (ɛ), optical conductivity (σopt), dissipation factor (tan δ) and relaxation time (τ) were determined.

Ultra-Narrow Phosphorene Nanoribbons Produced by Facile Electrochemical Process.

Phosphorene nanoribbons (PNRs) have inspired strong research interests to explore their exciting properties that are associated with the unique two-dimensional (2D) structure of phosphorene as well as the additional quantum confinement of the nanoribbon morphology, providing new materials strategy for electronic and optoelectronic applications. Despite several important properties of PNRs, the production of these structures with narrow widths is still a great challenge. Here, a facile and straightforward approach to synthesize PNRs via an electrochemical process that utilize the anisotropic Na+ diffusion barrier in black phosphorus (BP) along the [001] zigzag direction against the [100] armchair direction, is reported. The produced PNRs display widths of good uniformity (10.3 ± 3.8nm) observed by high-resolution transmission electron microscopy, and the suppressed B2g vibrational mode from Raman spectroscopy results. More interestingly, when used in field-effect transistors, synthesized bundles exhibit the n-type behavior, which is dramatically different from bulk BP flakes which are p-type. This work provides insights into a new synthesis approach of PNRs with confined widths, paving the way toward the development of phosphorene and other highly anisotropic nanoribbon materials for high-quality electronic applications.

Unfolding the conductivity reversal n- to p-type in phosphorus-doped ZnO thin films by spin-on dopant (SOD) process

Phosphorus doping induced p-type doping in ZnO thin films based on spin-on dopant (SOD) process is reported in this article. Owing to the reduced dependence on the conventional amenities for diffusion/ion-implantation doping, the SOD process provides a simple and cheap doping method. The effect of SOD process temperature on conductivity ZnO thin films is investigated by altering the temperature from 700°C to 1000°C. Systematic field emission scanning electron microscopy analysis demonstrates the impact of doping temperature on the morphological properties of SOD. The x-ray diffraction measurements reveal that the p-type ZnO thin films had (002) preferred crystal orientation. At the same time, x-ray photoelectron spectroscopy validated the formation of the PZn–2VZn complex, which was responsible for the acceptor behaviour of films. Moreover, the photoluminescence spectra tracked down that the origin of 3.35 and 3.31 eV emission peaks is due to the acceptor bound exciton and free-electron to acceptor level transitions, respectively. Finally, an elevated hole concentration of 2.09 × 1016 cm−3 is achieved with a resistivity of 1.14 Ω-cm at 800°C doping temperature. However, the film doped at 900°C and 1000°C showed n-type behaviour due to the generation of high concentration donor defects. Here, we successfully demonstrate that the SOD process has great potential to produce high-quality p-type ZnO thin films suitable for optoelectronic devices applications.

Enhanced Electrical Properties of Copper Nitride Films Deposited via High Power Impulse Magnetron Sputtering.

High Power Impulse Magnetron Sputtering (HiPIMS) has generated a great deal of interest by offering significant advantages such as high target ionization rate, high plasma density, and the smooth surface of the sputtered films. This study discusses the deposition of copper nitride thin films via HiPIMS at different deposition pressures and then examines the impact of the deposition pressure on the structural and electrical properties of Cu3N films. At low deposition pressure, Cu-rich Cu3N films were obtained, which results in the n-type semiconductor behavior of the films. When the deposition pressure is increased to above 15 mtorr, Cu3N phase forms, leading to a change in the conductivity type of the film from n-type to p-type. According to our analysis, the Cu3N film deposited at 15 mtorr shows p-type conduction with the lowest resistivity of 0.024 Ω·cm and the highest carrier concentration of 1.43 × 1020 cm−3. Furthermore, compared to the properties of Cu3N films deposited via conventional direct current magnetron sputtering (DCMS), the films deposited via HiPIMS show better conductivity due to the higher ionization rate of HiPIMS. These results enhance the potential of Cu3N films’ use in smart futuristic devices such as photodetection, photovoltaic absorbers, lithium-ion batteries, etc.