Evolution of Stress With Film Thickness in Co Films on InP(001)

We investigated the stress evolution of a Co/InP(001) by a highly sensitive optical deflection-detecting system in an ultra high vacuum (UHV) chamber. Stress results are analyzed and discussed by correlating to the growth morphology obtained from scanning tunneling microscopy (STM) measurements and to the structure of the Co/InP obtained from high resolution transmission electron microscopy (HRTEM) measurements. Abrupt compressive stress, which is seen at the initial stage of the Co growth, might be due to the effect of the adsorption of Co on the InP. Subsequent tensile stress is closely related to the formation of continuous film by the coalescence of Co islands on the InP as shown in STM images. In addition, it is observed from HRTEM images that the lattice relaxation along the c-axis of hcp Co has an effect on tensile stress.