Determination of optical constants and inhomogeneity of optical films by two-step film envelope method

A simple two-step film envelope method has been proposed to determine the optical constants and small inhomogeneity of the optical films, which uses maximum envelopes and minimum envelope of the normal incidence transmittance of the two-step film. The two-step films were prepared by stopping the deposition process in the middle of the designed sputtering time, and then, after a full cooling down to room temperature, repeating the same deposition process again to complete the whole preparation of the films. The optical constants of Nb2O5–TiO2 mixed films were calculated by two-step film envelope method and traditional envelope method. The experimental results demonstrate that the average refractive index and extinction coefficient calculated by two-step film envelope method are more accurate than those calculated by the traditional envelope method

EFFECT OF PASSING ELECTRIC CURRENT ON THE ELECTRICAL AND OPTICAL PROPERTIES OF ITO FILMS IN AIR

The effect of passing electric current on the electrical and optical properties of indium tin oxide (ITO) films in air has been studied. Resistivities of the ITO films deposited by direct current magnetron sputtering on glass substrates were about 10.5 × 10-4Ωcm (group A) and 4.3 × 10-4Ωcm (group B). A constant electric current i between 30 and 150 mA was applied to the films in air for 3 h. The results show that there is a critical current (icri) for each group sample. icri of group A is 60 mA and icri of group B is 90 mA. When i > icri, the electrical performance declines and optical transmittance increases for the electric annealed sample. However, both the electrical and optical performances may be improved for the annealed film when i ≤ icri. It is found that the variations in electrical and optical properties of the films strongly depend on the electric power applied to ITO films.Annealing, electric current, indium tin oxide, optical and electrical properties

High White Light Photosensitivity of SnSe Nanoplate-Graphene Nanocomposites

Abstract The multi-functional nanomaterial constructed with more than one type of materials has gained a great attention due to its promising application. Here, a high white light photodetector prototype established with two-dimensional material (2D) and 2D nanocomposites has been fabricated. The 2D-2D nanocomposites were synthesized with SnSe nanoplate and graphene. The device shows a linear I-V characterization behavior in the dark and the resistance dramatically decreases under the white light. Furthermore, the photosensitivity of the device is as large as 1110% with a rapid response time, which is much higher than pristine SnSe nanostructure reported. The results shown here may provide a valuable guidance to design and fabricate the photodetector based on the 2D-2D nanocomposites even beyond the SnSe nanoplate-graphene nanocomposites

Additional file 1: of Controllable Growth of the Graphene from Millimeter-Sized Monolayer to Multilayer on Cu by Chemical Vapor Deposition

Supplementary information. Figure S1. (a) The TEM image shows the corner of the graphene domains. (b–e) Selected area electron diffraction (SAED) data for small regions indicated 1 to 4. These SAED data confirm the single-crystalline structure of the graphene domains as they have the same set of sixfold symmetric diffraction points. Figure S2. The optical microscopy images of the multilayer graphene with increasing size in the center region grown by decreasing hydrogen concentration and keeping the methane for constant (0.5 sccm CH4). (a) 38 sccm H2; (b) 29 sccm H2. Figure S3. The deconvolution of the 2D band of the (a) monolayer, (b) bilayer, (c) trilayer, and (d) tetralayer graphene with Lorentzians function as shown in Fig. 3a. Figure S4. The optical microscopy images of the multilayer graphene with non-Bernal stacking transferred to SiO2. Figure S5. The deconvolution of the 2D band of the (a) monolayer, (b) bilayer, (c) trilayer, and (d) tetralayer graphene with Lorentzians function as shown in Fig. 3b. Figure S6. The G (a) and 2D (b) peak position of the multilayer grahene with Bernal and non-Bernal stacking order as shown in Fig. 3a and b, respectively. Figure S7. The I2D/IG value of the multilayer graphene with Bernal and non-Bernal stacking order as shown in Fig. 3a and b, respectively. Figure S8. The typical EDS spectrum of the probe site on the nanoparticle and not on the nanoparticle. Figure S9. The optical microscopy images of the multilayer graphene growth with 32 sccm H2, 0.5 CH4 at different time. (a) 10 min, (b) 20 min, (c) 40 min. (DOC 6452 kb