Formation of huge in-plane anisotropy of intrinsic stress by off-axis growth of diamond

摘要

The present study shows that the heteroepitaxial growth of diamond by chemical vapour deposition (CVD) on Ir/YSZ/Si(111) substrates with off-axis angles of few degrees can generate intrinsic stress with huge anisotropy of several GPa in the diamond films. For all investigated off-axis directions and angles, a plane stress state with a perpendicular component σ_(33) ～ 0 GPa is derived by X-ray diffraction. The size and direction of the associated in-plane stress tensor components exhibit a unique dependency on the off-axis tilt direction. They can combine the simultaneous presence of tensile and compressive stress within a layer. Stress anisotropy increases with the off-axis angle. For diamond with off-axis tilt towards [110] and [112], the principal axes of the tensor are parallel and perpendicular, respectively, to the projection of the off-axis direction into the film plane, whereas for [110] they are rotated by an angle of ～30°. For a consistent explanation of this complex behaviour, it is suggested that the measured stress is generated by the combined action of growth parameter controlled effective climb of dislocations and off-axis growth induced dislocation tilting. It is supposed that the described mechanism is not only valid for diamond CVD but also contributes to anisotropic stress formation in other semiconductor materials grown on vicinal surfaces.