Coherence Improvement of Dual-Lens Electron Holography

Abstract

Abstract Coherence is one of the limiting factors in off-axis electron holography applications. This paper reports methods to improve coherence ∼18-fold by using a smaller biprism and implementing a direct electron counting camera (K-camera) in combination with an imaging filter system. We achieved 0.4 nm fringe spacing with a 1.5 μm field-of-view and ∼33% fringe contrast. The maximum coherence number, N′, of ∼1.8 × 103 was achieved, where N′ is defined as the number of fringes times fringe contrast. High spatial resolution junction profile images (nm scale) of n-channel and p-channel field-effect transistors (nFET and pFET) are demonstrated with a large field-of-view (μm scale).