Adsorption and Decomposition of Chemisorbed Propylene on the Si(100)- (2x1) Surface: A Laser-Induced Thermal Desorption Study

Deuterated propylene C3D6 chemisorption and decomposition on the Si100-2x1 surface has been studied in ultrahigh vacuum by using laser induced thermal desorption LITD and temperature programmed desorption techniques TPD. Propylene was found to adsorb molecularly at 110 K and to remain as an undecomposed molecular adsorbate up to approx. 500 K. As the surface temperature is increased, the propylene can both thermally desorb and decompose. ultimately producing a SiC thin film LITD was used to study C3D6 and D2 desorption as a function of surface temperature during temperature programming. Slow heating leads to strongly enhanced C3D6 decomposition compared to fast heating by laser irradiation. The decomposition of propylene is apparently a multistep process because deuterium is released from the chemisorbed propylene and its fragments over a temperature range from approx. 450 to 850 K. D2 desorption from the decomposition of C3D6 occurs at higher temperature compared to that observed for chemisorbed deuterium.