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

Abstract

Under ultraviolet (UV) illumination of GaAs with photon energies above 3.5 eV, Si–H complexes are known to be efficiently dissociated at room temperature. 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 concentration of dissociated Si–D complexes is 10–20 times below the concentration of dissociated Si–H complexes. This strong isotope effect is discussed under the light of recent excitation models of Si–H(D) bonds at the surface of silicon and at the Si/SiO2 interface.

Electron-beam-induced dissociation of B–D complexes in diamond

“…Moreover, 102 K is well below the temperature of 823 K at which thermal dissociation of B-D pairs begins, 20 making it quite unlikely. Mechanism ͑ii͒ would consist in the excitation by hot electrons of the bonding electron of a B-D pair to an antibonding state, leading to a repulsive force on the H. However, in this case, the dissociation yield has been shown to be independent of the electron current 17,19 which is in contradiction with the results of Fig. 2.…”

Strong isotope effects in the ultraviolet light-induced reactivation of dopants in hydrogenated or deuterated n-GaAs :Si

“…This means that, in the illumination intensity range that we have investigated, the complex dissociation yield is relatively independent of the illumination power density. We shall discuss later the situation of the hydrogenated and deuterated structures at 100 K. For low photon densities, one observes two major features: a quasilinear variation of N s with the incident photon density and an important isotope effect in the dissociation yield of Si-H and Si-D complexes at 300 K and 100 K. This result confirms our previous results [5] where the plasma exposed n-GaAs:Si,H epilayers were not etched before UV illumination while those presented here are reported on samples etched on the first 150 nm. This means that the strong isotope factor is related to the Si-H(D) dissociation yield and is not damage-related.…”

“…A strong isotope effect has been discovered for the stability of Si-H bonds under hot electron excitation at the Si/SiO 2 interface of CMOS transistors [6]. Recently, we found a strong isotope factor in the dissociation kinetics of Si-H and Si-D complexes in GaAs under UV illumination at 300 K [5]. In this work, we shall show that this isotope effect exists at 300 K and also at 100 K.…”

“…Moreover, the investigation of the isotope factor of the H(D)-dopant complex dissociation rate is expected to give some insight into the physical mechanisms responsible for the excitation of the H(D)-dopant complexes. Thermal excitation usually displays a small isotope effect, the D-dopant complexes being slightly more stable than the H-dopant complexes [5]. However, under hot electron injection in reverse bias n-GaAs:Si Schottky diodes, Si-D complexes are significantly more stable than Si-H complexes [3].…”

Hydrogen loss ina−Si:C:Hlayers induced by MeV ion beam irradiation

“…[19][20][21] For, as in the work of Foley et al using a scanning tunneling microscope, 19 we are dealing with the interaction of Si-H ͑Si-D͒ bonds with lowenergy electrons, which in our case are emitted in the primary track by the passing ion. However, in our case we calculate that we lose one bonded H atom per 1-10 electrons, emitted in the track, whereas one apparently needs 10 5 -10 6 electrons to stimulate hydrogen or deuterium desorption from a Si-surface.…”