A self-limiting layer-by-layer etching technique for 2H-MoS₂

Abstract

We report controlled layer-by-layer removal of large-area, sulfurized, single-crystal molybdenum disulfide (MoS 2) films using a digital etching technique, which utilizes oxidation and removal of the oxidized layer. We demonstrate a self-limiting oxidation process where Mo oxide covered the surface of MoS 2. A constant etching rate of one monolayer/cycle and the uniformity of the etching process were also verified. We show that the etching of an integer number of MoS 2 layers can be precisely controlled. No noticeable film quality degradation was observed after multiple cycles of digital etching, as confirmed by Raman mapping of the ratio of the E 1 2g and A 1g peak intensities.

Lithographically patterned metallic conduction in single-layer MoS2 via plasma processing

“…28 Additionally, oxidation of sulfur vacancies has been demonstrated as a self-limiting half-reaction in atomic-layeretching applications. 33 Owing to the favorable energetics and self-limiting nature, the~10-min atmospheric exposure was believed to be sufficient to oxidize the sulfur vacancies, and additional atmospheric exposure time would have resulted in minimal additional oxidation.…”

Low‐Damaged Layer‐by‐Layer Etching of Large‐Area Molybdenum Disulfide Films via Mild Plasma Treatment

“…[ 12,13,15,16 ] There are only a few reports on using large‐area MoS 2 films to control its layer. [ 17,18 ] Lee et al. used specialized methodology using oxygen plasma treatment and wet etching process to perform layer‐by‐layer etching of MoS 2 films.…”

“…used specialized methodology using oxygen plasma treatment and wet etching process to perform layer‐by‐layer etching of MoS 2 films. Their method showed no noticeable film degradation, [ 18 ] but no electrical properties were characterized to prove whether their method is feasible for practically large‐scale electronics. [ 18 ] Therefore, it is highly necessary to develop the methodology to tune the number of layers of large‐area MoS 2 films with minimizing structural defects and showing reasonable performance of resultant devices.…”

“…Their method showed no noticeable film degradation, [ 18 ] but no electrical properties were characterized to prove whether their method is feasible for practically large‐scale electronics. [ 18 ] Therefore, it is highly necessary to develop the methodology to tune the number of layers of large‐area MoS 2 films with minimizing structural defects and showing reasonable performance of resultant devices. Herein, we report layer‐by‐layer etching of MoS 2 films, using mild sulfur hexafluoride (SF 6 ) plasma treatment.…”

“…The obtained roughness of the pristine MoS 2 is around 0.5 nm, which is similar to that of previous report. [ 18 ] Upon the plasma treatment for 30 s, the roughness slightly decreases (0.38 nm). Such decreased roughness is presumably attributed to removal of unreacted MoO x or impurities on surface of MoS 2 films during the synthesis.…”