Comparison between deep level defects in GaAs induced by gamma, 1 MeV electron, and neutron irradiation

Abstract

The deep level transient spectroscopy technique has been employed to follow closely the effect of 1–300 Mrad 60Co γ irradiation on the deep electron traps in undoped vapor-phase-epitaxy n-type GaAs. The 1 Mrad γ-irradiated Schottky device was identical to the as-grown or control device, with only two electron traps EL2 (Ec−0.820 eV) and EL3 (Ec−0.408 eV) detected. At a γ dose of 5 Mrad, two additional electron traps EL6 (Ec−0.336 eV) and E2 (Ec−0.128 eV) were observed. As the γ doses were increased to ≥10 Mrad, a third electron trap E1 (Ec−0.033 eV) was observed, and the single exponential EL2 capacitance transient became a double exponential, indicating two deep levels lying at Ec−0.820 eV (EL2/EL2-A) and Ec−0.843 eV (EL2-B). The trap concentration of EL2-A remained unchanged up to a γ dose of 50 Mrad before starting to increase slowly as the γ dose was increased to ≥100 Mrad. In contrast, the EL2-B trap concentration was found to increase by 32 times, reaching 2.6×1014 cm−3 at 300 Mrad from a low 8.0×1012 cm−3 at 10 Mrad when it was first observed, whereas for the 1 MeV electron irradiation with low electron fluence of 1014 e cm−2, the EL6, E2, E1, and the double exponential EL2 were detected at the same time. There was no sign of EL2-B, EL3, EL6, E2, or E1, but an additional broad U band was observed after irradiation with 1 MeV neutrons. The results of the γ and neutron irradiation suggest that the presence of the double exponential EL2 transients is not related to either EL6, E2, E1, or the U band, and is unlikely to be due AsGa→VGa+Asi but is probably caused by the AsGa complex defects involving an irradiation defect. The defect concentration of trap E1 increased strongly from 5.4×1013 cm−3 at 10 Mrad to 9.3×1014 cm−3 at 100 Mrad, and E2 increased from 2.1×1013 cm−3 at 5 Mrad to 6.7×1014 cm−3 at 100 Mrad.

Capacitance transient spectroscopy models of coupled trapping kinetics among multiple defect states: Application to the study of trapping kinetics of defects in heavy-ion-damaged silicon

“…22 Multistable defect configurations and internal conversion between them have been reported for interstitial-carbon substitutional-group-V-atom pair defects in electron irradiated silicon. 23 Traps with two charge states which present strong coupling to the lattice have been observed in a variety of semiconductors, for example, in Si, 24 InP, 10 Hg y Cd 1Ϫy Te, 25 GaAs, 26 and Al x Ga 1Ϫx As, 27 which were mainly analyzed through DLTS studies without attempting such model formalism. As the DLTS technique is based on the temperature scanning method, inherent limitations of the spectral line shape due to a temperaturedependent prefactor in the capacitance transient, and the possible presence of a thermally activated capture process, may lead to a misinterpretation of the result.…”

Effect of gamma-ray irradiation on structural properties of GaAsN films grown by metal organic vapor phase epitaxy

“…The irradiation of GaAs with high-energy radiation particles can produce lattice defects in the form of vacancies, defect clusters, and dislocations. Lai et al [20] reported that gamma-ray irradiation resulted in the creation of complex defects in the Ga-As system. The main effect of these lattice defects on GaAs-based devices is the creation of recombination centers, which are known to reduce the minority-carrier lifetime.…”

Structural, optical and electrical properties of ion beam irradiated cadmium selenate nanowires

“…with minimum ecological disruption and resistant to radiation. In case of semiconductors, the radiation leads to production of lattice defects in the form of vacancies, defect clusters and dislocations that influence the energy levels and alter the material parameters [6][7][8]. These defects play significant role in the performance of the devices such as sensors, solar cells, metal-oxidesemiconductor junctions, schottky diodes etc.…”