Isothermal deep-level transient spectroscopy was combined, with the application of uniaxial compressive stresses along <111>, in order to study the effect of stress upon the electronic state of a Pt-dihydrogen complex and the kinetics of charge-state dependent motion of H around the Pt atom during stress-induced reorientation. It was found that the application of a stress split the isothermal deep-level transient spectroscopy peak into 2 components. The electronic energy of the short-time component increased linearly with <111> compressive stress according to 0.035eV/GPa; thus indicating an antibonding character. The reorientation kinetics of the complex under an applied stress were also studied, and it was found that the defect aligned, at 78 to 88K, in a configuration with the smallest activation energy of the level, only when the level was not occupied by an electron. This indicated a clear charge-state effect upon the local motion of H around the Pt atom. That is, the H was mobile only in the singly-negative charge state of the complex. An activation energy of 0.27eV was estimated for H motion around the Pt atom under a stress of 0.6GPa. Three structural models were considered. Among them, a model in which two H atoms directly bonded to the Pt atom was the most plausible candidate. In this structure, defect reorientation required no bond switching but only rotation of the whole Pt-H2 entity. A possible mechanism for charge-state dependent reorientation was that, if the electronic state with antibonding character was occupied by an electron, the two H atoms might be displaced outwards; thus probably retarding their motion in the reorientation.

Effect of Uniaxial Stress on the Electronic State of a Platinum-Dihydrogen Complex in Silicon and Charge-State Dependent Motion of Hydrogen during Stress-Induced Reorientation. Y.Kamiura, K.Sato, Y.Iwagami, Y.Yamashita, T.Ishiyama, Y.Tokuda: Physical Review B, 2004, 69[4], 045206