Study of Some Optical and Electrical Properties of Heavily Doped Silicon Layers

Abstract

It is well known that the solubility of most dopants can be noticeably increased in silicon by pulsed laser annealing of the implanted layers. Here, we have investigated the evolution of some optical and electrical properties of such heavily doped layers as a function of implanted dose, trying to separate effects due to the high doping from those resulting from defects or precipitates. P-type silicon wafers have been implanted with 80 KeV arsenic ions at doses of up to 1017 cm-2 and annealed by a pulsed ruby and YAG laser, giving pulses of 20 and 100 ns duration, respectively and depositing energies up to 2.5 J.cm-2. U.V. and visible light (250 and 500 nm) reflectance, as well as ellipsometry (632.8 nm) measurements have been performed as well as dark I - V and C - V characteristics. These investigations indicate that by increasing the implanted dose, the doping level first increases until near surface defects and precipitates modify the optical as well as the electrical properties of the heavily doped layers. The generation of these defects has been followed by RBS in random and channelling conditions

Superconducting properties of silicon nanostructures

“…Therefore, the trigonal ESR spectrum observed seems to be evidence of the dynamic magnetic moment that is induced by the exchange interaction between the small hole bipolarons which are formed by the negative-U reconstruction of the shallow boron acceptors, 2B 0 → B + + B -, along the <111> crystallographic axis (Fig. 6a) (Slaoui et al 1983;Gehlhoff et al 1995;Bagraev et al 2002). These small hole bipolarons localized at the dipole boron centers, B + -B -, seem to undergo the singlet-triplet transition in the process of the exchange interaction through the holes in the Si-QW thereby leading to the trigonal ESR spectrum (Fig.…”

Superconductor Properties for Silicon Nanostructures

“…Therefore, the trigonal ESR spectrum observed seems to be evidence of the dynamic magnetic moment that is induced by the exchange interaction between the small hole bipolarons which are formed by the negative-U reconstruction of the shallow boron acceptors, 2B 0 →B + + B -, along the <111> crystallographic axis (Fig. 7a) (Slaoui et al, 1983;Gehlhoff et al, 1995;Bagraev et al, 2002). These small hole bipolarons localized at the dipole boron centers, B + -B -, seem to undergo the singlet-triplet transition in the process of the exchange interaction through the holes in the Si-QW thereby leading to the trigonal ESR spectrum (Figs.…”

“…The decrease in R(λ) compared with the data of the silicon single crystal and the drops in the position of the peaks at the wavelengths of λ=354 and 275 nm are observed. The above peaks are related to the transitions between -L valleys and in the vicinity of the point X in the Brillouin zone, with the former of the above peaks being assigned to the direct transition ' 25 -' 2 , whereas the latter peak is attributed to the transition X 4 -X 1 (Slaoui et al, 1983). An analysis of the spectral dependence of the reflection coefficient shows that the presence of the microcavities formed by the selfassembled microdefects with medium size reduces R(λ) most profoundly in the shortwavelength region of the spectrum (200-300 nm).…”

Quantum Supercurrent Transistors in Silicon Quantum Wells Confined by Superconductor Barriers

“…The decrease in R() compared with the data of the silicon single crystal and the drops in the position of the peaks at the wavelengths of  = 354 and 275 nm are observed. The above peaks are related to the transitions between Γ-L valleys and in the vicinity of the point X in the Brillouin zone, with the former of the above peaks being assigned to the direct transition Γ' 25 -Γ' 2 , whereas the latter peak is attributed to the transition X 4 -X 1 [17]. An analysis of the spectral dependence of the reflection coefficient shows that the presence of the microcavities formed by the self-assembled microdefects with medium size reduces R() most profoundly in the short-wavelength region of the spectrum (200 -300 nm).…”

“…Therefore, the trigonal ESR spectrum observed seems to be evidence of the dynamic magnetic moment that is induced by the exchange interaction between the small hole bipolarons which are formed by the negative-U reconstruction of the shallow boron acceptors, 2B 0  B + + B -, along the <111> crystallographic axis (Figure 6(a)) [5,12,17]. These small hole bipolarons localized at the dipole boron centers, B + -B -, seem to undergo the singlettriplet transition in the process of the exchange interaction through the holes in the Si-QW thereby leading to the trigonal ESR spectrum (Figures 5(a), (b), (c) and (d)).…”