Layer-By-Layer Growth and Growth Manipulation

Abstract

Technical applications of thin films and thin film systems often necessitate atomically sharp interfaces between the film and the vacuum or between different film layers. To mention a few examples: Magnetic coupling through non-magnetic layers depends sensitively on the spacer layer thickness [526]; tunneling devices require insulator spacer layers of precisely controlled thickness (implying negligible roughness) [527]; and spin dependent electron transport through interfaces is strongly correlated with the interface roughness [528-530]. Thus, generally it is desirable to grow thin films in a layer-by- layer fashion resulting in smooth interfaces. Occasionally, however, the opposite may be required, and a rough interface resulting from mound growth may be advantageous, e. g. for shadow deposition of nanomagnets [531]. Although in practical thin film applications mostly heteroepitaxial and polycrystalline films are used, investigations on how to influence the thin film growth morphology in homoepitaxy uncover the means supplied by growth kinetics towards the goal of creating thin film interfaces with purposely defined morphological properties.

When Shannon opened the shutter controlling the Ga oven to begin the growth sequence, we observed with amazement that the diffraction spots were pulsing in brightness. John R. Arthur [525]