C.J. Dale

Correlation of Particle-Induced Displacement Damage in Silicon

Correlation is made between the effects of displacement damage caused in several types of silicon bipolar transistors by protons, deuterons, helium ions, and by 1 MeV equivalent neutrons. These measurements are compared to calculations of the nonionizing energy deposition in silicon as a function of particle type and energy. Measurements were made of displacement damage factors for 2N2222A and 2N2907A switching transistors, and for 2N3055, 2N6678, and 2N6547 power transistors, as a function of collector current using 3.7 - 175 MeV protons, 4.3 - 37 MeV deuterons, and 16.8 - 65 MeV helium ions. Long term ionization effects on the value of the displacement damage factors were taken into account. In calculating the energy dependence of the nonionizing energy deposition, Rutherford, nuclear elastic, and nuclear inelastic interactions, and Lindhard energy partition were considered. The main conclusions of the work are as follows: 1) The ratio of the displacement damage factors for a given charged particle to the 1 MeV equivalent neutron damage factor, as a function of energy, falls on a common curve which is independent of collector current. 2) Deuterons of a given energy are about twice as damaging as protons and helium ions are about eighteen times as damaging as protons.

Particle-induced bit errors in high performance fiber optic data links for satellite data management

Experimental test methods and analysis tools are demonstrated to assess particle-induced bit errors on fiber optic link receivers for satellites. Susceptibility to direct ionization from low LET particles is quantified by analyzing proton and helium ion data as a function of particle LET. Existing single event analysis approaches are shown to apply, with appropriate modifications, to the regime of temporally (rather than spatially) distributed bits, even though the sensitivity to single events exceeds conventional memory technologies by orders of magnitude. The cross-section LET dependence follows a Weibull distribution at data rates from 200 to 1000 Mbps and at various incident optical power levels. The LET threshold for errors is shown, through both experiment and modeling, to be 0 in all cases! The error cross-section exhibits a strong inverse dependence on received optical power in the LET range where most orbital single events would occur, thus indicating that errors can be minimized by operating links with higher incident optical power. Also, an analytic model is described which incorporates the appropriate physical characteristics of the link as well as the optical and receiver electrical characteristics. Results indicate appropriate steps to assure suitable link performance even in severe particle orbits. >

High energy electron induced displacement damage in silicon

New measurements of displacement damage factors for electron-irradiated (4 to 53 MeV) bipolar silicon transistors have extended the correlation between nonionizing energy loss and damage factors reported previously another three orders of magnitude downward, to cover a total of six decades. To first order, the correlation remains linear for both n- and p-type silicon, but deviations are observed and explained in terms of differences in the fraction of initial vacancy interstitial pairs that recombines. These differences correlate linearly with the low-energy component of the PKA spectrum. Deep level transient spectroscopy measurements show oxygen- and dopant-related defect levels as well as divacancies. Defect concentrations scaled linearly with gain degradation, and no differences were seen between electron and proton plus neutron irradiated material. The results are consistent with a damage mechanism involving migration of vacancies to form well-separated stable defects. >

Displacement damage in GaAs structures

High-energy knock-on atoms produced by incident protons are much more important in determining the total nonionizing energy deposited in GaAs than in Si, due to the relative size of the Lindhard correction for partitioning the recoil energy. High-energy recoils are mainly produced by inelastic nuclear interactions between the incident protons and the target atoms. A review of previous calculations indicates that both the fast cascade and the evaporation phases of the elastic interaction contribute to the average energy of the recoiling ion. New calculations are presented for the energy dependence of the nonionizing energy deposited in GaAs as a result of inelastic interaction with protons over the energy range 10-1000 MeV. These calculations are combined with the previously determined contribution from elastic interactions to obtain the energy dependence of the total nonionizing energy deposited in GaAs by protons. The calculation is compared with both new and earlier experimental data for ion-implanted GaAs resistors irradiated with protons over the energy range 40-188 MeV, in order to form a basis whereby proton displacement effects in GaAs structures can be predicted. It is shown that results obtained for 10 MeV protons, for example, can be used to predict results to be expected at much higher energies. >

Displacement damage extremes in silicon depletion regions

Measurements of proton-induced dark current increases in a Si CID (charge injection device) imager have been made following displacement damage by 12- and 63-MeV protons. Populations of 61504 pixels optimize statistics and make possible the first detailed study of rare events. To this end, extreme value statistics allow a quantitative treatment and lead to characterization of a rare device-dependent mechanism. Data comparing the response of two similar CID structures suggest that electric-field-enhanced emission is responsible for the largest dark current increases in the CID structure with the higher electric fields. Comparisons between observations and estimates based on new calculations of the recoil spectrum parameters demonstrate that the largest dark current increases can be predicted in the absence of high fields. In this case the inelastic recoil component of the recoil spectrum plays a dominant role in determining the large dark current increases. Implications for other materials are discussed. >

Energy Dependence of Proton-Induced Displacement Damage in Gallium Arsenide

Nonionizing energy deposition in gallium arsenide has been calculated for protons with energies ranging from 1 to 1000 MeV. The calculations are compared with new experimental results for ion implanted gallium arsenide resistors and Hall samples irradiated with protons in the energy range 1 to 60 MeV. Results are also compared with recent studies of proton induced displacement damage in silicon.

A comparison of Monte Carlo and analytic treatments of displacement damage in Si microvolumes

In this paper, we compare Monte Carlo and analytic calculations of displacement damage resulting from inelastic proton reactions in Si. These comparisons include the nonionizing energy loss rate, the mean recoil damage energy spectra, and their associated variance. In the limit of bulk material, both approaches are in good agreement. Sensitive volumes shrink and incident proton energies increase, the ranges of the spallation recoil fragments approach the smallest dimension of the microvolume, and the pixel-to-pixel damage variance increases rapidly. In this regime, a Monte Carlo approach is used to describe the damage energy distribution. Indeed, we show that such simulations predict the 63 MeV proton-induced dark current histograms more accurately than present analytic methods. The Monte Carlo code is also used to explore ground test fidelity issues for devices with small sensitive volumes. >

Proton-induced displacement damage distributions and extremes in silicon microvolumes charge injection device

An analytic approach for determining the pixel-to-pixel distribution of particle-induced damage and damage extremes in microvolumes representative of focal plane array pixel geometries is presented. Comparisons between predicted and measured dark current distributions in a silicon charge injection device (CID) show excellent agreement for 12- and 63-MeV proton-induced damage. The calculated and measured damage extremes are compared using extreme value statistical analysis. The calculations reveal how high-energy recoils from proton-induced nuclear reactions strongly influence the pixel-to-pixel variation in damage as well as the damage extremes. A comparison between Si and GaAs pixels with equal volumes and equal 12-MeV proton fluences indicates that both the average damage and its variance are significantly greater in GaAs. >

The generation lifetime damage factor and its variance in silicon

The generation damage factor and its variance for silicon are determined for proton energies of 12, 22, and 63 MeV, and for fission neutrons. Measurement of the variance is made for the first time using 61504 pixels of a charge-injection device. The variance is an intrinsic characteristic of damage due in part to differences in numbers and magnitudes of atomic recoils produced in each pixel. Calculations of the variance due to the recoil spectrum show that the magnitude of the relative variance is determined by Coulombic recoils. In fact, the experimental relative variance is almost two orders of magnitude less for fission-neutron-induced dark current increases than for the proton case. The relative variance was found to decrease as the proton energy was increased. The calculation shows that this trend is caused by the inelastic contribution to the relative variance of the recoil spectrum. >

Space radiation effects on optoelectronic materials and components for a 1300 nm fiber optic data bus

The authors report energy-dependent proton and Co-60 test results and analysis assessing performance of In/sub 0.53/Ga/sub 0.47/As photodetectors and In/sub 0.71/Ga/sub 0.29/As/sub 0.61/P/sub 0.39/ laser diodes for satellite applications. Displacement damage degradation in the InGaAs photodetector is interpreted using DLTS. Novel calculations of the nonionizing energy loss (NIEL) for protons in InGaAs allow damage assessment using a general technique for evaluating displacement damage in orbit. Data are presented confirming the proton energy dependence of NIEL in a III-V material over the energy range of interest for spacecraft. Effects in optoelectronic devices due to total dose and ionization transients are also discussed. >