La. Okada et al., ISOTHERMAL H-2 DESORPTION-KINETICS FROM SI(100)2X1 - DEPENDENCE ON DISILANE AND ATOMIC-HYDROGEN PRECURSORS, Applied surface science, 82-3, 1994, pp. 410-416
Citations number
36
Categorie Soggetti
Physics, Condensed Matter","Chemistry Physical","Materials Science, Coatings & Films
Isothermal H2 desorption kinetics from the Si(100)2 x 1 surface were s
tudied using laser-induced thermal desorption (LITD) techniques. Disil
ane (Si2H6) and atomich hydrogen were used as the hydrogen precursors.
Atomic hydrogen deposits only hydrogen adatoms and H2 subsequently de
sorbs from a nearly atomically flat Si(100)2 x 1 surface. Disilane dep
osits both hydrogen and silicon adatoms that may produce an atomically
rough Si(100) surface. This surface roughening with silicon adatoms s
imulates silicon chemical vapor deposition and may affect the H2 desor
ption kinetics. The isothermal LITD studies revealed first-order H2 de
sorption kinetics for both precursors. An activation barrier of E(d) =
57.2 +/- 2.6 kcal/mol and a pre-exponential factor of nu(d) = 2.21 x
10(15 +/- 1) s-1 were measured for the atomic hydrogen precursor. An a
ctivation barrier of E(d) = 54.3 +/- 2.3 kcal/mol and a pre-exponentia
l factor of nu(d) = 2.32 x 10(14 +/- 1) s-1 were determined for the di
silane precursor. Within the experimental error, the isothermal H2 des
orption kinetics were not significantly affected by the hydrogen sourc
e. The similar desorption kinetics are attributed to the surface mobil
ity of the silicon adatoms deposited with disilane. The silicon adatom
s can either diffuse to nearby step edges or form Si(100)2 x 1 islands
on the underlying Si(100)2 x 1 surface. The first-order H2 desorption
kinetics are explained by the concerted desorption of H2 from two hyd
rogen atoms prepaired on the same silicon dimer on the Si(100)2 1 surf
ace.