It depends on many factors, such as temperature, tunneling condition. As said above, first find a flat area ( for example 20x20 nm^2 or larger), then zoom in. Usually, lower temperature, better image.

As already mentioned, it depends on many factors, including the condition of the tip you are using in the experiment. How to get good atomic resolution STM images is difficult to teach, I would recommend you first try getting atomic resolution images of simpler reference samples such as Ag or Au surfaces, then move to your MoS2 sample. Another factor could be the quality of the surface of your exfoliated sample.

You need to scan at not too large distances. Try 0.1 V and 1-3 nA. Then the feedback-loop also needs to be fast enough, but not let it oscillate it by itself. At room- temperature the temperature drift is a main obstacle too, so do not scan too slow. Finally the tip state is decisive. You can alter the tip state by gently dipping the tip into the surface, this works fine on metal surfaces. On layered material on the other hand you might have flakes at the tip which prevent high resolution.

Please mentioned that which STM you are using. Based on that other people will guide you that how to get the atomic resolution while you scanning. First of all ensure the condition of tip i.e. it is sharp enough (not a blunt tip). If it is sharp enough then you can play with scan size, bias voltage and tunneling current values. As I have used Omicron VT STM and Unisoku LT STM, so in our case we get atomic resolution on daily basis.

semiconductors or metals which are easy to get an atomic resolution image using STM? Rakesh Kumar Sharma Sir do you also get STS spectra with your omicron VT-STM very easily.