Some Features of the Structure of Silicon Single Crystals Irradiated by Large Fluences of Fast Light Ions of Gases

Секция 2. Радиационные эффекты в твердом теле = Section 2. Radiation Effects in SolidsStructural study of silicon irradiated by large fluences of light gas ions has shown how the degree of damage in Si, both in the ion passage region and in the braking area, increases and become more complicated with increasing energy and mass of ions. For hydrogen ions the stress line in the braking region is narrowest and its width grows almost linearly with energy. For ions of deuterium and helium, this dependence is weaker and deviates from linear. Additional stress lines depended on the value of ion current (intensity of irradiation) were observed in the pictures of selective etching. For current densities up to 0.45 μA/cm2, the second etched line of stresses appeared at the distance equal to the twice length of the run of protons from the surface. With an increase in the current density up to 1 μA/cm 2 , this line was not observed, at 3 μA/cm2 the part of Si (with thickness that corresponds to the ion path depth) in the irradiation process was exfoliated from main volume. The number of extra etched lines is maximal for helium and depends on the temperature of irradiation. Increase in the temperature (over 100 oС) leads to disappearance of additional stress lines. Detail study with gradual selective etching (in the step of 30 μm) from an irradiated surface has shown the distribution of structural defects in the plane of the proton braking region of silicon, irradiated with fluence 10 17 cm –2 at T ≤ 100 оС and annealed for 0.5 h at 580 оC. With deepening into Si volume the irradiated region associated with radiation defects was gradually decreasing and completely disappeared at the depth of 150 μm behind the braking line. At the depth of nearly 35 μm behind the braking line, the growth layers of matrix Si were detected

Electrical and optical characteristics of GaP diodes, irradiated with 2 MeV electrons

Serial green and red GaP light emitting diodes were studied. Structures were irradiated at room temperatures with 2 MeV electrons in pulse mode and electrical characteristics were measured at 77 – 300 K. It was observed the new stage of negative differential resistance at low temperature (90 K) and the current (< 103 mA) interval, additionally to known S-type instability. Luminescence characteristics at different temperatures and injection levels were given for all types’ diodes. Dose dependencies of luminescence intensity on electron dose and its restoring after irradiation were also presented

Influence of 2 MeV electrons irradiation on gallium phosphide light-emitting diodes reverse currents

Results of reverse electrophysical characteristics study of red and green LEDs, initial and irradiated with 2 MeV electrons were given. It was found that reverse current was predominantly caused by carriers tunneling at Urev ≤ 9 V, and by the avalanche multiplication at Urev ≥ 13 V, in the range U = 9 ÷ 13 V both mechanisms are available. Current increase at high voltage areas (Urev > 19 V) is limited by the base resistance of diode. In the case of significant reverse currents (I > 1 mA) irradiation of diodes leads to the shift of reverse current-voltage characteristics into the high voltages direction

Peculiarities of electrooptical characteristics of gallium phosphide light-emitting diodes in high injection level conditions

Electroluminescence of green N-doped gallium phosphide light-emitting diodes was studied. The negative differential resistance region in the current-voltage characteristics was found at low temperature (Т ≤ 90 К). Possible reason of this phenomenon is the redistribution of recombinational flows between annihilation channels on isolated nitrogen atoms and annihilation channel on the NN1 pairs

Surface distribution of the emitting intensity of GaP light-emitting diodes

Microplasma breakdowns of red and green GaP diodes were studied. It has been shown that tunneling was the main component of reverse current at the beginning of the breakdown while an avalanche current prevailed at highs breakdown current. Microplasma spectrum is considered to be the result of the overlapping of hot carrier emitting and recombination amitting of impurity level-valence band. 2 MeV electron irradiation leads to the de-crease of microplasma number due to the radiation defect creating

Effect of neutron irradiation on characteristics of power ІnGaN/GaN light-emitting diodes

Effect of the reactor fast neutron flux (E = 2 MeV, Ф = 2⋅1014 n/cm2) on the current-voltage, capacitance-voltage characteristics, the electroluminescence intensity of power ІnGaN/GaN LEDs on the SіC and AuSn/Si substrates are studied. It was revealed that radiation hardness of InGaN/GaN heterostructures depend on the substrate

Radiation defects in neutron irradiated silicon with high oxygen concentration

Abstract In silicon material with oxygen concentration in the range (4–9)×10 17 cm −3 , grown by the CZ method and irradiated by reactor neutrons, the interstitial oxygen mainly participates in A-center (V+O) creation. A-center concentration is linearly dependent on neutron fluence up to Φ =10 18 n/cm 2 , value at which saturation occurs caused not by the exhaustion of dissolved oxygen but rather by vacancy-interstitial atom annihilation competitive mechanisms. A-center annealing ( T >300°C) does not lead to the full restoring of interstitial oxygen concentration. Repeating neutron irradiation and annealing causes a decrease of oxygen complex activity and the silicon behaves as a low-oxygen material