In-situ growth monitoring with scanning force microscopy during pulsed laser deposition

摘要

Imaging and mapping “new” land, species, organisms and processes created possibilities to manipulate and control them. Microscopes enabled imaging objects and processes that go beyond the human senses as vision, sense and hearing. This information is required to understand physical and chemical processes such as deposition and growth. Currently, there is also a clear need to monitor the surface morphology during deposition. To image and map (non)conducting surfaces with atomic resolution, Scanning Force Microscopy (SFM) can be used. With physical vapor deposition techniques such as Pulsed Laser Deposition (PLD) thin films of almost any material such as metal oxides can be deposited. Finding the optimum deposition parameters, for material systems, is traditionally done by trial and error. This can be a tedious and time-consuming process especially when information on composition and morphology is lacking during growth. Diagnostic information during deposition of materials such as metal oxides is up to now mostly derived from diffraction methods such as Reflection High Energy Electron Diffraction (RHEED), Surface X-Ray Diffraction (SXRD) and Low Energy Electron Diffraction (LEED). These instruments are based on diffraction and measure the periodic arrangement of the surface atoms. However, the local surface morphology such as the island density, the island size distribution and island shapes can not be directly measured on a microscopic scale as opposed to imaging techniques such as Scanning Probe Microscopy (SPM). This instrument has a high spatial resolution, but is usually not combined with deposition techniques and merely used ex-situ*. This hampers quantitative studies to describe the nucleation and growth because it is difficult to measure the evolution of the same microscopic surface location and the surface morphology evolution could be influenced† by the cooling procedure to room temperature, ambient exposure and ex-situ sample preparation. This thesis describes a setup for in-situ growth monitoring with SFM during Pulsed Laser Deposition (PLD).