By plasma-enhanced chemical vapor deposition, a molybdenum disulfide (MoS2 ) thin film is synthesized directly on a wafer-scale plastic substrate at below 300 °C. The carrier mobility of the films is 3.74 cm(2) V(-1) s(-1) . Also, humidity is successfully detected with MoS2 -based sensors fabricated on the flexible substrate, which reveals its potential for flexible sensing devices.

Two-dimensional (2-D) metal dichalcogenides like molybdenum disulfide (MoS 2 ) may provide a pathway to high-mobility channel materials that are needed for beyondcomplementary metal-oxide-semiconductor (CMOS) devices. Controlling the thickness of these materials at the atomic level will be a key factor in the future development of MoS 2 devices. In this study, we propose a layer-by-layer removal of MoS 2 using the atomic layer etching (ALET) that is composed of the cyclic processing of chlorine (Cl)-radical adsorption and argon (Ar) + ion-beam desorption. MoS 2 etching was not observed with only the Clradical adsorption or low-energy (< 20 eV) Ar + ion-beam desorption steps; however, the use of sequential etching that is composed of the Cl-radical adsorption step and a subsequent Ar + ion-beam desorption step resulted in the complete etching of one monolayer MoS 2 . Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) indicated the removal of one monolayer MoS 2 with each ALET cycle; therefore, the number of MoS 2 layers could be precisely controlled by using this cyclical etch method. In addition, no noticeable damage or etch residue was observed on the exposed MoS 2 .

Bulk layers of MoS2 were synthesized in situ on a polymer substrate at low temperature for electrochemical biosensing.

A CoFeB thin film composing a magnetic tunneling junction of CoFeB/MgO/CoFeB was etched in an inductively coupled plasma ͑ICP͒ etching system using CO/NH 3 gas mixtures, and its etch characteristics were compared with those of the CoFeB thin film etched using Cl 2 /Ar. When Cl 2 /Ar was used to etch the CoFeB thin film, even though its etch rate was faster than that of the CoFeB thin film etched using CO/NH 3 , a rough CoFeB surface could be observed due to the corrosion of the CoFeB surface during exposure to the air in addition to the significant change of surface composition. On the other hand, no corrosion of the CoFeB thin film was observed after the etching using CO/NH 3. When the ratio of CO/NH 3 was varied, the highest etch rate of 12 nm/min could be observed at the ratio of 1:3 compared to about 4 nm/min for CO or NH 3 at the ICP source power of 700 W, bias power of 300 W, and 5 mTorr of operating pressure. The highest etch rate was related to the formation of volatile metal carbonyls between metal and CO, where NH 3 appeared to assist the easier formation of metal carbonyl by preventing the dissociation of CO into C and CO 2 .