| Standard Number | PWI 113-170 |
|---|---|
| Organization |
International Electrotechnical Commission
|
| Level | International |
| Category | Test Method | Characterization | Measurement |
| Status |
|
This part of IEC 60607 establishes three standardized methods to determine the key control characteristic • number of layers for MoS2 films on a substrate by • Raman spectroscopy. This standard presents three complementary methods for determining the number of layers in MoS2 layers on a substrate: Method A analyzes the Raman peak position of low-frequency Raman modes, and Method B analyzes the difference between peak position of high-frequency Raman modes, and Method C measures the Raman intensity from the underlying silicon substrate. The three methods can be employed individually but combining both methods enhances accuracy and extends the detection range for the number of layers. – The method is intended to be used for MoS2 layers prepared by mechanical exfoliation, but also can be used with care for other high quality MoS2 layers, such as MoS2 layers prepared by chemical vapor deposition. – The method can be used for MoS2 layers with 2H phase on a substrate. Its lateral size should be at least 2 µm. – Method A is effective for 2 to 10 layers which gives excellent contrast; however it is not applicable for monolayer region. – Method B is effective for 1 to 5 layers; but becomes less reliable with more layers due to smaller difference. – Method C can detect up to 10 layers but oxidized silicon substrate is required. Method C is also valid for 3R and 1T’ phase and other twisted stacking configuration. – The comparison of the three methods can be found in Annex A.
