Radiative and Magnetically Stimulated Evolution of Nanostructured Complexes in Silicon Surface Layers

Abstract

The effect of a weak magnetic field (B = 0.17 T) and X-irradiation (D < 520 Gy) on the rearrangement of the defective structure of near-surface p-type silicon layers was studied. It was established that the effect of these external fields increases the positive accumulated charge in the region of spatial charge (RSC) and in the SiO2 dielectric layer. This can be caused by both defects in the near-surface layer of the semiconductor and impurities contained in the dielectric layer, which can generate charge carriers. It was found that the near-surface layers of the barrier structures contain only one deep level in the silicon band gap, with an activation energy of Ev + 0.38 eV. This energy level corresponds to a complex of silicon interstitial atoms SiI+SiI. When X-irradiated with a dose of 520 Gy, a new level with the energy of Ev + 0.45 eV was observed. This level corresponds to a point boron radiation defect in the interstitial site (BI). These two types of defect are effective in obtaining charge carriers, and cause deterioration of the rectifier properties of the silicon barrier structures. It was established that the silicon surface is quite active, and adsorbs organic atoms and molecules from the atmosphere, forming bonds. It was shown that the effect of a magnetic field causes the decay of adsorbed complexes at the Si–SiO2 interface. The released hydrogen is captured by acceptor levels and, as a result, the concentration of more complex Si–H3 complexes increases that of O3–Si–H.

Mechanically Stimulated Changes in Surface Electrical Conductivity of X-Irradiated Silicon Crystals

“…Under the action of the strain potential due to the discrepancy between the parameters of the Al and Si lattices, the value of electrical conductivity in the near -surface layer of the crystal increases and, as a rule, by 50-70% the mobility of charge carriers increases [13,[15][16]. In addition, the metal film deposited on the Si surface contributes to the formation of a site in the near-surface layer, which is an effective getter for deep-level structural defects [9,13]. Such defects can be impurity atoms moved from the sample volume to the near-surface region, Si atoms that leave the lattice nodes at interstitial positions, and vacancies generated at such outputs [11].…”

“…The redistribution of the concentration of charge carriers, and the evolution of structural defects in deformed and X-ray irradiated p-Si crystals is largely determined by the perfection of the starting material, the presence and mobility of dislocations, which are drains for charges and defects, especially in the near-surface region [8]. In addition, a surface with sprayed metal contacts is an effective getter for deep-level structural defects [9,10]. The discrepancy between the parameters of the crystal lattices and the metal contact sprayed on it leads to the appearance of local mechanical stresses [11].…”

“…The discrepancy between the parameters of the crystal lattices and the metal contact sprayed on it leads to the appearance of local mechanical stresses [11]. Radiation exposure of crystals and devices of semiconductor electronics is accompanied by the accumulation of charges on internal defects, changes in surface states, the formation of internal electric fields and fields in the semiconductor-dielectric contact area, and so on [6,9]. These and other mechanical and radiation-stimulated effects stimulate changes in the electrophysical parameters of crystals.…”