Si(113) hydrogen desorption kinetics: a temperature programmed desorption study

Hydrogen desorption kinetics from Si(I 1 3) surfaces were investigated usin g D-2 temperature programmed desorption (TPD). For this purpose, clean Si(I 1 3)3 X 2 wafers were exposed to atomic deuterium at 200 degreesC for time s sufficient to provide D coverages OD ranging up to saturation, theta (D,s at). Corresponding low-energy electron diffraction patterns transform from 3 x 2 to 3 x 1-D to I x 1 with increasing theta (D). TPD spectra from Si(1 1 3) surfaces with theta (D) = theta (D,sat) consist of a first-order desor ption feature (beta (1)) centered at 515 degreesC and a second-order desorp tion peak (beta (2)) at 405 degreesC. beta (2) is assigned to D-2 desorptio n, with an activation energy of 2.16 eV, from a dideuteride surface phase w hile beta (1) is due to desorption from monodeuteride. The beta (1) peak co nsists of two components: beta (1,t) which arises due to first order, as a result of ir-bond induced ordering, D-2 desorption from tetramers and beta (1,ad) which is due to second-order D-2 desorption from adatoms and second- layer surface atoms. Both beta (1) components have activation energies of 2 .58 eV. Following monodeuteride desorption, the clean Si(I 13) surface agai n exhibits a 3 x 2 reconstruction. The TPD results are explained based upon previously proposed models for the Si(I 13)3 x 2 reconstructed surface. (C ) 2001 Published by Elsevier Science B.V.