[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

As an interesting layered material, molybdenum disulfide (MoS2) has been extensively studied in recent years due to its exciting properties. However, the applications of MoS2 in optoelectronic devices are impeded by the lack of high-quality p–n junction, low light absorption for mono-/multilayers, and the difficulty for large-scale monolayer growth. Here, it is demonstrated that MoS2 films with vertically standing layered structure can be deposited on silicon substrate with a scalable sputtering method, forming the heterojunction-type photodetectors. Molecular layers of the MoS2 films are perpendicular to the substrate, offering high-speed paths for the separation and transportation of photo-generated carriers. Owing to the strong light absorption of the relatively thick MoS2 film and the unique vertically standing layered structure, MoS2/Si heterojunction photodetectors with unprecedented performance are actualized. The self-driven MoS2/Si heterojunction photodetector is sensitive to a broadband wavelength from visible light to near-infrared light, showing an extremely high detectivity up to ≈1013 Jones (Jones = cm Hz1/2 W−1), and an ultrafast response speed of ≈3 μs. The performance is significantly better than the photodetectors based on mono-/multilayer MoS2 nanosheets. Additionally, the MoS2/Si photodetectors exhibit excellent stability in air for a month. This work unveils the great potential of MoS2/Si heterojunction for optoelectronic applications.

MoS2/Si Heterojunction with Vertically Standing Layered Structure for Ultrafast, High‐Detectivity, Self‐Driven Visible–Near Infrared Photodetectors

Solid-state electronics

This paper reports the synthesis and detailed characterization of graphite thin films produced by thermal decomposition of the (0001) face of a 6H-SiC wafer, demonstrating the successful growth of single crystalline films down to approximately one graphene layer. The growth and characterization were carried out in ultrahigh vacuum (UHV) conditions. The growth process and sample quality were monitored by low-energy electron diffraction, and the thickness of the sample was determined by core level x-ray photoelectron spectroscopy. High-resolution angle-resolved photoemission spectroscopy shows constant energy map patterns, which are very sharp and fully momentum-resolved, but nonetheless not resolution limited. We discuss the implications of this observation in connection with scanning electron microscopy data, as well as with previous studies.

Synthesis and characterization of atomically-thin graphite filmson a silicon carbide substrate,

Graphene’s unique physical structure, as well as its chemical and electrical properties, make it ideal for use in sensor technologies. In the past years, novel sensing platforms have been proposed with pristine and modified graphene with nanoparticles and polymers. Several of these platforms were used to immobilize biomolecules, such as antibodies, DNA, and enzymes to create highly sensitive and selective biosensors. Strategies to attach these biomolecules onto the surface of graphene have been employed based on its chemical composition. These methods include covalent bonding, such as the coupling of the biomolecules via the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide reactions, and physisorption. In the literature, several detection methods are employed; however, the most common is electrochemical. The main reason for researchers to use this detection approach is because this method is simple, rapid and presents good sensitivity. These biosensors can be particularly useful in life sciences and medicine since in clinical practice, biosensors with high sensitivity and specificity can significantly enhance patient care, early diagnosis of diseases and pathogen detection. In this review, we will present the research conducted with antibodies, DNA molecules and, enzymes to develop biosensors that use graphene and its derivatives as scaffolds to produce effective biosensors able to detect and identify a variety of diseases, pathogens, and biomolecules linked to diseases.

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Recent advances in graphene-based biosensor technology with applications in life sciences

Temperature dependence of characteristic parameters of the H-terminated Sn/p-Si(1 0 0) Schottky contacts

The current–voltage (I–V) characteristics of CrNiCo alloy Schottky contacts on a molecular-beam epitaxy n-GaAs substrate have been measured over the temperature range of 130–330 K and have been interpreted based on the assumption of a Gaussian distribution of barrier heights due to barrier height inhomogeneities that prevail at the interface. It is shown that the occurrence of Gaussian distribution of then barrier heights is responsible for the decrease of the apparent barrier height Φb0, increase of the ideality factor n and nonlinearity in the activation energy plot at low temperatures. A Φb0 vs 1/T plot was drawn to obtain evidence of a Gaussian distribution of the barrier heights, and values of Φb0(T=0)=1.02 eV and σ0=0.105 V for the mean barrier height and zero-bias standard deviation, respectively, have been obtained from this plot. Thus, a modified ln(I0/T2)−q2σ02/2k2T2 vs 1/T plot gives Φb0(T=0) and A* as 1.02 eV and 5.13 A/cm2 K2, respectively, without using the temperature coefficient of the b...

Temperature dependent barrier characteristics of CrNiCo alloy Schottky contacts on n-type molecular-beam epitaxy GaAs

Electrical characterization of Au/n-ZnO Schottky contacts on n-Si

In this study, we have attempted to interpret experimentally observed non-ideal AlpSi Schottky diode I-V and C−2−V characteristics which are due to an interface layer, interface states and fixed surface charge. A value of 0.68 eV for the barrier height qΦBo for AlpSi diodes without interface layer and fixed surface charge has been obtained from C−2−V characteristics and a value of 0.20 eV for the neutral level of the surface states has been found. Furthermore, the value of the barrier height qΦBp without fixed surface charge and the effective barrier height qΦBp,o are separately obtained from C−2-V characteristics. In addition, values of interface state density Dit have been calculated.

Abdulmecit Turut

Papers

Temperature dependence of characteristic parameters of the H-terminated Sn/p-Si(1 0 0) Schottky contacts

Temperature dependent barrier characteristics of CrNiCo alloy Schottky contacts on n-type molecular-beam epitaxy GaAs

Electrical characterization of Au/n-ZnO Schottky contacts on n-Si

Parameter extraction from non-ideal C−V characteristics of a Schottky diode with and without interfacial layer

Fabrication and electrical characteristics of Schottky diode based on organic material