Hidenori Ohyama

Impact of high energy particles on InGaP/InGaAs pseudomorphic HEMTs

Irradiation damage and its recovery behavior resulting from thermal annealing in InGaP/InGaAs pseudomorphic HEMTs, subjected to a 20 MeV alpha ray and 220 MeV carbon, are studied for the first time. The drain current and effective mobility decrease after irradiation, while the threshold voltage increases in positive direction. The degradation of device performance increases with increasing fluence. The decrease of the mobility is thought to be due to the scattering of channel electrons with the induced lattice defects and also to the decrease of the electron density in the two dimensional electron gas (2DEG) region. The influence of the radiation source on the degradation and recovery is discussed by comparison with 1 MeV electron and 1 MeV fast neutron exposures with respect to the number of knock-on atoms and the nonionizing energy loss (NIEL). Isochronal thermal annealing for temperatures ranging from 75 to 300/spl deg/C shows that the device performance degraded by the irradiation recovers completely.

Impact of neutron irradiation on optical performance of InGaAsP laser diodes

Abstract Results are presented of an extended study on the degradation and recovery behavior of optical and electrical performance and on induced lattice defects of 1.3 μm InGaAsP double channel planar buried heterostructure laser diodes with an In 0.76 Ga 0.24 As 0.55 P 0.45 multi-quantum well active region, subjected to a 1 MeV fast neutron and 1 MeV electron irradiation. The degradation of the device performance increases with increasing fluence. Two hole capture traps with near midgap energy level in the In 0.76 Ga 0.24 As 0.55 P 0.45 multi-quantum well active region are observed after a 1×10 16 n/cm 2 irradiation. These deep levels are thought to be associated with a Ga vacancy. The decrease of optical power is related to the induced lattice defects, leading to a reduction of the non-radiative recombination lifetime and of the carrier mobility due to scattering. The difference in radiation damage between 1 MeV fast neutrons and 1 MeV electrons is discussed taking into account the non-ionizing energy loss (NIEL). The radiation source dependence of performance degradation is attributed to the difference of mass and the probability of nuclear collision for the formation of lattice defects. The decreased optical power recovers by thermal annealing, and the recovery increases with increasing annealing temperature. The optical power recovers by 45% for 1 MeV neutron irradiation with a fluence of 1×10 15 n/cm 2 after a 300°C annealing.

Induced lattice defects in InGaAsP laser diodes by high-temperature gamma ray irradiation

Abstract Results of a study are presented on the degradation of InGaAsP laser diodes by high-temperature γ-ray and electron irradiation. It is shown that the optical power decreases after irradiation. One hole trap is observed in the In0.76Ga0.24As0.55P0.45 multi-quantum well active region after room-temperature γ- or e−-irradiation. The deep levels are thought to be associated with the Ga-vacancy. The decrease of the optical power is ascribed to the carrier removal and to the mobility reduction by carrier scattering, through the induced lattice defects. The change of device performance and the introduction rate of lattice defects decrease with increasing irradiation temperature. The optical power after a 200°C irradiation is nearly identical as before, for the fluence range studied.

Factors determining the damage coefficients and the low-frequency noise in MeV proton-irradiated silicon diodes

In this paper, the factors determining the reverse current and the recombination lifetime damage coefficients in high-energy proton-irradiated Si junction diodes are studied. These factors are: the particle energy, the crystal growth technique and corresponding starting material quality, and the substrate doping density and type. The observed macroscopic device degradation is discussed in view of the microscopic damage factor, the nonionizing energy loss (NIEL). Finally, the impact of proton irradiation on the low-frequency noise in forward operation is reported. Several experimental factors lead to the conclusion that the change in the flicker noise is related to the created ionization damage in the lateral oxide isolation at the periphery of the diode rather than to the bulk displacement damage.

Impact of induced lattice defects on performance degradation of AlGaAs/GaAs p-HEMTs

Abstract Irradiation damage and its recovery behavior resulting from thermal annealing in AlGaAs/GaAs pseudomorphic HEMTs, subjected to 1-MeV electrons, 1-MeV fast neutrons and 220-MeV carbon, are studied. The drain current and effective mobility decrease after irradiation, while the threshold voltage increases in positive direction. The decrease of the mobility is thought to be due to the scattering of channel electrons with the induced lattice defects and also to the decrease of the electron density in the two-dimensional electron gas (2DEG) region.

Radiation defects in Sti silicon diodes and their effects on device performance

Abstract Results are presented of a deep level transient spectroscopy (DLTS) investigation of the radiation induced lattice defects in shallow trench isolation (STI) silicon diodes by 20xa0MeV proton and 2xa0MeV electron irradiation. The correlation between the deep levels and the post-rad device performance will be studied, together with the recovery behavior by isochronal thermal annealing. It will be demonstrated that the reverse and forward current increase after irradiation, which is caused by a decrease of the generation and recombination lifetime, respectively. Two electron capture levels were observed in meander diodes after 10 14 xa0pxa0cm −2 proton irradiation. The degraded device performance recovers by isochronal thermal annealing and correlates well with the annealing of the radiation-induced electron traps. During the annealing, the electron traps transform in other more stable defect centers.

Radiation damage in AlGaAs/GaAs pseudomorphic HEMTs

The degradation of AlGaAs/GaAs pseudomorphic HEMTs by 220-MeV carbon, 1-MeV electron and neutron irradiation and their recovery by subsequent isochronal annealing are investigated and compared with results obtained on irradiated InGaP/InGaAs p-HEMTs.

Factors determining the lifetime damage coefficients and the low-frequency noise in MeV proton irradiated silicon diodes

The impact of several factors, related to the doping density, the substrate type and the thermal pre-treatment on the proton radiation damage coefficients of Si diodes is discussed and verified experimentally. The diode parameters investigated are the leakage current density, the recombination lifetime and the low-frequency noise current spectral density. Proton irradiations have been performed in the energy range 10 MeV to 100 MeV and in the fluence range of 5·109 to 4·1011 cm−2, typical for space applications. The obtained coefficients are compared with theoretical NIEL predictions.

Radiation damage of N-MOSFETS fabricated in a BiCMOS process

Results are presented of a study on the radiation damage and its recovery behavior resulting from thermal annealing of n-MOSFETs fabricated in a 0.8-μm single-well BiCMOS process, subjected to γ-rays, 1-MeV electrons and 1-MeV neutrons. After irradiation, the base (substrate) current and interface trap density normally increase with increasing fluence. This result points out that both ionization damage in the gate oxide and lattice defects in the p-well are induced by the irradiation. The interface trap density recovers by 85% for γ-ray irradiation with a fluence of 1×108 rad, after a 300 °C annealing.

Effect of irradiation in InGaAs photo devices

Results are presented of an extended study on the degradation of electrical and optical performance and the induced lattice defects of In0.53Ga0.47As p-i-n photodiodes, subjected to a 20 MeV alpha-ray irradiation. The difference in radiation damage with 1 MeV fast neutrons and 1 MeV electrons is discussed taking into account the energy transfer. The radiation source dependence of performance degradation is attributed to the difference of mass and the probability of nuclear collision for the formation of lattice defects.