High-resolution (HR) SEM
By high-resolution (HR) SEM, we denote imaging of the sample with high accuracy, in order to faithfully represent the surface morphology. Instrumentally, there are two typical requirements. Firstly, a field emission gun and suitable electron optics that converge the beam in to a narrow (e.g. 1 nm diameter) electron probe with high brightness. Secondly, a SE detector that eliminates any possible signal from backscattered electrons, since their large interaction volume degrades image resolution (see BE imaging). On the XL30-SFEG, these requirements are achieved with the use of an immersion lens, with which the sample inhabits the field of the pole piece, and an in-lens electron detector.