Morphological phases of tungsten thin films on gallium arsenide

Tungsten thin layers deposited on GaAs single crystal substrates in ultrahigh vacuum display a variety of distinct morphologies depending on substrate temperature and metal layer thickness. We present a preliminary study of some of these structures, including boundary layers in the metal, columnar growth, and an unusual phase that shows a strong orientational correlation with the substrate. We also discuss the effects of these structures on applications of W metallization to devices and processes of III-V semiconducting compounds.