Strong isotope effects in the dissociation kinetics of Si-H and Si-D complexes in GaAs under ultraviolet illumination

Under ultraviolet (UV) illumination of GaAs with photon energies above 3.5 eV, Si-H complexes are known to be efficiently dissociated at room temperat ure. Studying the dissociation kinetics of Si-H and Si-D complexes in GaAs, we have observed that, for a given incident UV photon density, the concent ration of dissociated Si-D complexes is 10-20 times below the concentration of dissociated Si-H complexes. This strong isotope effect is discussed und er the light of recent excitation models of Si-H(D) bonds at the surface of silicon and at the Si/SiO2 interface. (C) 1999 American Institute of Physi cs. [S0003-6951(99)04326-0].