Biaxially textured Mo films with diverse morphologies by substrate-flipping rotation

Abstract

A class of nanostructured Mo thin films was grown by DC magnetron sputtering using arobust substrate rotation mode called ‘flipping rotation’. In this rotation mode, thesubstrate is arranged to rotate continuously at a fixed speed around an axis lying withinand parallel to the substrate. The incident flux is perpendicular to the rotational axis, andthe incident flux angle changes continuously. Mo nanostructured films, grown underdifferent rotation speeds with three orders of magnitude spread (ranging from 0.008 to24 rotation min − 1), different flipping directions (clockwise and counter-clockwise), and different endingdeposition angles, were characterized using scanning electron microscopy (SEM) andreflection high energy electron diffraction (RHEED) surface-pole-figure techniques. Despitetheir very different morphologies, such as ‘C’-shaped, ‘S’-shaped, and vertically alignednanorods, the same biaxial texture with an average out-of-plane dispersion of ∼ 15° was observed. In contrast, we showed that only a fiber-textured Mo film was obtained byusing the conventional rotation mode where the oblique incident flux angle was fixed withthe substrate rotating around the surface normal.