Investigation of irradiated monolithic transistors for space applications

In this paper experimental results on radiation effects on a BICMOS high speed commercial technology, manufactured by STMicroelectronics, are reported. Bipolar transistors were irradiated by neutrons, ions, or by both of them. Fast neutrons, as well as other types of particles, produce defects, mainly by displacing silicon atoms from their lattice positions to interstitial locations, i.e. generating vacancy-interstitial pairs, the so-called Frenkel pairs (FP). Defects introduce trapping energy states which degrade the common emitter current gain β. The gain degradation has been investigated for collector current Ic between 1 μA and 1 mA. It was found a linear dependence of Δ(1/β)=1/βi−1/β (where βi and β are the gain after and before the irradiation) as a function of the concentration of FP. The bipolar transistors made on this technology have shown to be particularly radiation resistant. Both base and collector currents have been also systematically investigated

Study of radiation effects on bipolar transistors

Abstract In this paper it was shown that the irradiation with neutrons and carbon ions leads to gain degradation in bipolar transistors due to generation of defects. The density of these generated defects is independent of the type of irradiation (neutrons or carbon ions). Thus, it is possible to evaluate Δ(1/β), once the expected Frenkel pair density is known. The dependence of the damage constant on collector current is a power law function, with the exception of the lateral pnp transistors, that shows a higher sensitivity to radiation and a different behaviour. Neutrons give a smaller density of Frenkel pairs (CF) than the two sorts of carbon ions of high energy (CHE) and medium energy (CME). It was found that CME causes a higher concentration of CF. The calculated ratio R=CF/Φ, where CF is the Frenkel pair density and Φ fluence does not depend on Φ, for a given type of radiation. However, it depends on the incoming particle type. Its smallest calculated value was obtained for neutrons (R=6.1×10), which increases to 1.25×103 for CHE and to 1.1×104 for CME

Defect creation kinetics in swift heavy ions, protons and electrons irradiated germanium

N-type lightly doped germanium has been irradiated at room temperature with different particles: swift heavy ions, protons and electrons. Hall effect measurements have been carried out versus either the temperature (at a given fluence) or the fluence (at room temperature). Using the level positions determined by DLTS results previously reported, we extract from the Hall coefficient simulation at low doses the creation kinetics of the irradiation-induced defects. These defects are typically at room temperature the A-centre, the E-centre and the divacancy complexes. At higher doses, in the case of electron irradiation, these simulations are still feasible using only the previous defects mentioned above since the material leads towards a quasi-intrinsic state. But we point out that it is necessary in the case of proton and swift heavy ion irradiations to add an acceptor level in the forbidden band probably associated with a multivacancy defect. Indeed, in these cases, the material becomes p-type. Finally, the experimental introduction rates are compared to the theoretical ones. It appears that the relative damage creation efficiency is not very different from a projectile to another, proving that there is no strong dependence on the electronic energy loss

Optical properties of Cr^2+:ZnSe single crystal and film

International audienc

Luminescence properties of Cr2+:ZnSe: Comparison between a single crystal and a film deposited by RF magnetron co-sputtering

International audienc

Growth and luminescence study of Cr²⁺: ZnSe films deposited by radio-frequency magnetron co-sputtering

International audienc

Polymerization and surface modification by low pressure plasma technique

A durable water repellent, stain resistant or flame retardant character can be conferred to polyacrylonitrile (PAN) textiles by using the plasma induced graft polymerization technique. The monomers used are perfluoroalkylacrylate, (meth)acrylate phosphates, and phosphonates which are well known to be effective for the waterproofing and the fireproofing of polymeric substrates, respectively

Optimization of ZnSe–SiO2 nanostructures deposited by radio-frequency magnetron sputtering: Correlations between plasma species and thin film composition, structural and microstructural properties

International audienc

Optimized conditions for an enhanced coupling rate between Er ions and Si nanoclusters for an improved 1.54-μm emission

International audienc