SU584626A2 - The method of generating hole color centers in dielectric - Google Patents

Description

one

The invention relates to the field of experimental and technical physics and can be applied when performing research in radiation chemistry, in solid state physics, and also in radiation technology of materials.

Of particular importance is the possibility of generating stable pure hole centers for solid state physics, as it allows us to study only hole conductivity and hole properties of dielectrics. In practice, the possibility of creating dielectrics with high electrical resistance and hardening dielectrics due to the generation of non-equilibrium stable concentration of hole color centers opens up.

A known electrochemical method of generating holes in dielectrics uses current passing from the cathode plate to the anode tip through a heated dielectric, as a result of which electrons are drawn from the dielectric, which leads to the formation of holes in the main energy zone and stable hole color centers Ij.

With known methods of radiative staining, excluding positron ones, as a result of ionizing collisions of charged particles with atoms of a lattice, an equilibrium concentration of free electrons and holes is generated, which leads to the formation of both hole and electronic centers, confirmed by destruction over time or upon dielectric annealing.

A known contactless method of generating holes in dielectrics of any type and composition, this method consists in the following: first, the dielectric is irradiated with a stream of positrons, which leads to an excessive concentration of holes, and then the irradiated dielectric is subjected to annealing, which makes it possible to isolate pure hole stable color centers 2J.

The disadvantages of this method are the long duration of the processes (several days) and the fact that hole centers generate only in the dielectric region limited by the positron mean free path.

In order to increase the expressivity of the method while simultaneously increasing the useful volume of the dielectric, the latter is preliminarily colored to a concentration of L centers of at least 10 cm.

Claims (2)

 leads to the formation of an equilibrium concentration of electron and hole centers. During the subsequent irradiation of the pre-cooled ionic crystals with a stream of positrons in them, in addition to the process of creating defects, there is a fifjouecc of radiation annealing of electronic color centers. In this case, the process of radiation annealing of colored samples under irradiation with nozitronamn occurs in both the part of the sample that is irradiated and that which is not irradiated by positrons. Until recently, fixing by the optical absorption spectra the destruction of the electron centers, the colors upon positron annealing, did not follow the behavior of the hole band of optical absorption. It turned out that during positron annealing of previously radiation-colored crystals, the hole band undergoes very insignificant changes, although this significantly suppresses the F and M bands of optical absorption. This is observed both for samples whose thickness is comparable to the range of positrons, and for samples whose thickness is much greater than the length of the free path of positrons. All this leads to the creation of a nonequilibrium concentration of hole color centers. Subsequent annealing of the radiation-annealed dielectric from a certain temperature, known for most dielectrics, leads to recombination of electrons and holes, which are in equilibrium concentration, to annealing of electron and hole color centers. As a result, stable pure hole centers remain in the dielectric, which can exist for a long time. For a proper understanding of radiation annealing under positron irradiation, it is necessary to emphasize that the destruction of electronic color centers, for example, F centers, cannot be associated with positron annihilation in F centers, since studying the mechanism of positron annihilation in radiation-colored KC1 ionic crystals, KVg , NaCl showed a low probability of positron annihilation at E centers compared to other radiation-induced defects. Even if all positrons are annihilated on P-electrons, the positron dose at which F-centers are annealed (positron / cm -) is clearly not enough to destroy F-centers (cm). It can be assumed that radiation defects formed during irradiation with positrons and -y-quats are involved in three main processes: in the process of radiation-stimulated annealing of “heavy radiation defects (vacancies, interstitial ions, etc.); in the process of movement of light radiation defects — electrons and holes in the field of excess positive charge created by the annihilation of positrons; in the process of coagulation and accumulation of "severe radiation defects. By pre-irradiation, it is necessary to create a concentration of F centers of at least 10 cm, since at lower concentrations of defects during positron irradiation, not the process of radiation annealing will prevail, but the process of generation and accumulation of defects. The invention The method of generating hole color centers in a dielectric according to ed. St. No. 432797, characterized in that, in order to increase the expressivity of the method while simultaneously increasing the useful volume of the dielectric, the dielectric is pre-radiation painted to a concentration of F-centers of at least 10 cm. Sources of information taken into account in the examination 1. A. Vorobiev A. A. Color centers in alkali-halide crystals. Tomsk, Ed. TGCH, 1968, p. 12. 2. USSR author's certificate number 432797, cl. G ORS 23/02, 18.12.72.