Physical and chemical data of WS2 platelets and thickness-dependent photoresponses

In this data article, the properties of WS2/ZnO type-I heterostructure which corresponds to the research article “Vertically trigonal WS2 layer embedded heterostructure for enhanced ultraviolet-visible photodetector” (Nguyen et al., 2018) are presented by characteristics of WS2 layer, diode properties, and thickness dependent photoresponses. The device performances under the effect of rapid thermal processing (RTP) is presented. The WS2 platelets grown by large area sputtering method (Nguyen et al., 2018) was characterized in term of morphology and chemical elements distribution by using transmission electron microscope (TEM), energy dispersive spectroscopy (EDS) and X-Ray photoelectron spectroscopy (XPS). Diode characterization of WS2/ZnO like rectifying ratio, ideal factor and barrier height are presented. The variation of photocurrent of ITO/WS2/ZnO/FTO/glass photodetector, its dependence on the WS2 thickness and influence of post- thermal treatment are presented.


Value of the Data
The data relates to chemical states of WS 2 platelet could be useful to study the defect engineering of WS 2 material WS 2 /ZnO type-I heterostructure design is efficient for the large scale transitional metal dichalcogenides (TMDs) for optoelectronics.
Effect of the thickness of WS 2 layer was investigated for the photocurrent profiles.

Data
The quantities of various oxidation states of tungsten are presented in Fig. 1 by using XPS measurement. Further, Fig. 2 shows the morphology of vertical WS 2 platelets grown by sputtering method [1] and the distribution of W and S in the WS 2 . The diode properties of WS 2 /ZnO structure includes the rectifying ratio, diode ideality factor and potential barrier height are presented in Fig. 3. In addition, the transient photocurrent profiles of WS 2 /ZnO device are presented in Fig. 4 (at 7 1 bias). The parameters used to simulate the band diagram of the WS 2 /ZnO heterostructure are summarized in the Table 1 for Solar Sell Capacitance Simulator (SCAPS) [1]. Later, considering properties of vertically grown WS 2 as well as WS 2

Sample preparation
The FTO glass was used as the substrate for the ITO/WS 2 /ZnO/FTO fabrication and was cleaned prior to the fabrication process described in Ref. [1].
The ZnO layer was fabricated according to conditions presented in Ref. [2].

Sample characterization
The quantities of various tungsten oxidation states are described in Fig. 1 by performing chemical analysis of the WS 2 platelets on the Si substrate using X-ray photoelectron spectroscopy (XPS, PHI 5000 VersaProbe-II, ULVAC). Property of vertical WS 2 layer was examining by transmission electron microscope (TEM, TALOS F200X) as presented by Fig. 2a. The chemical elemental mapping of WS 2 platelets are presented by Fig. 2b with the detail distribution of W and S elements characterized by Fig. 2c using energy dispersive spectroscopy (EDS, JEOL, JSM_7001F). The diode properties of WS 2 / ZnO structure (rectifying ratio, ideal factor and barrier height) are presented by Fig. 3. The currentvoltage property of WS 2 /ZnO device as presented by Fig. 3a was analyzed by using potentionstat/ galvanostat (PGStat, ZIVE SP1, WonA Tech) using linear sweep voltammetry. The barrier height of 0.06 V of WS 2 /ZnO heterostructure is obtained by analyzing the flat-band potential of WS 2 /ZnO heterostructure which determined from the Mott-Schottky characteristics as presented by Fig. 3b.  Fig. 4 presents the current-time property of the device at bias of 7 1. The illustration of band diagram of WS 2 /ZnO heterostructure which characterized by one-dimensional drift-diffusion equation solver program (SCAPS) [1] is based on material parameters presented by Table 1. The effects of RTP treatment and WS 2 deposition time on ITO/WS 2 /ZnO/FTO device performances were studied by analyzing current-time characteristics of the device using chronoamperometry. The frequency and power of the light source were modulated by using a function generator (MFG-3013A, MCH instruments). Fig. 5 presents the photocurrent of the device under different temperature conditions of RTP process. And the correlation between photocurrent of the device and WS 2 time deposition is presented by Fig. 6.