A SiC p-i-n junction betavoltaic was fabricated, and electrical power output under irradiation from an 8.5GBq P33 source was monitored over a period of four half-lives of the radioisotope. The open-circuit voltage (VOC) of the device was 2.04±0.02V, and the peak power (Pout) was 0.58±0.02μW (2.1±0.2μW∕cm2) at 1.60V. The conversion efficiency (ηconv) was 4.5%±0.3% and the normalized power output indicates no device degradation over more than 3months (four half-lives of the source).

Structural and optical properties of strainrelaxed InAsP/InP heterostructures grown by metalorganic vapor phase epitaxy on InP(001) using tertiarybutylarsine We have investigated the strain relaxation of intentionally lattice mismatched (Ϯ0.5%͒ GaInP layers grown on GaAs substrates by organometallic vapor phase epitaxy. Double axis x-ray diffraction was used to measure the relaxation in these epitaxial layers in perpendicular ͗110͘ directions as a function of thickness. For samples in tension, the difference in relaxation between ͓110͔ and ͓110͔ increases from 10% to 48% as the layer thickness increases from 7 to 28 times the critical thickness, h c . For samples in compression this difference is 28% at 24h c while no relaxation is measured for a sample at 6h c . These results indicate that strain relaxes anisotropically and that the anisotropy is more pronounced for samples in tension than in compression. Furthermore, the major relaxation axis was found to be ͓110͔ regardless of the sign of the strain. Reciprocal space maps, generated using triple axis x-ray diffraction, showed that the amount of microtilt of the epitaxial layers was also anisotropic. This anisotropy and the direction of the maximum dislocation density which was measured by cathodoluminescence and transmission electron microscopy, changed from ͓110͔ in tension to ͓110͔ in compression. The fact that the major relaxation axis remained stationary while the high misfit dislocation density direction rotated indicates that a substantial number of dislocations with Burgers vectors of the ''wrong sense'' for strain relief are formed in compressed epilayers. A model in which ␣ type dislocations are more mobile than the ␤ type misfit dislocations regardless of the sign of the strain is consistent with all of the experimental observations.

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(001) CZ silicon wafers were implanted with As+ at 100 keV to a dose of 1×1015/cm2 in order to produce a continuous amorphous layer to a depth of about 120 nm. Furthermore, the implant condition was such that the peak arsenic concentration was below the arsenic clustering threshold. Subsequently, a second As+ or Ge+ implant was performed at 30 keV to doses of 2×1015/cm2, 5×1015/cm2 and 1×1016/cm2, respectively, into the as-implanted samples. All of the samples were annealed at 800 °C for 1 h. The second implant was designed to be contained within the amorphous region created by the initial implant. The second As+ implant was also designed to provide the additional arsenic needed to exceed the critical concentration for clustering at the projected range. Of the three samples with the dual As+ implant the clustering threshold was exceeded for the two lower doses while the SiAs precipitation threshold was exceeded at the highest dose. In the case of the dual As+/Ge+ implants the clustering and precipitation thresholds were not reached. Since arsenic and germanium are similar in mass the extent of damage created by these implants would be comparable. The implanted and annealed specimens were analyzed using secondary ion mass spectroscopy and transmission electron microscopy. The difference in the defect evolution and the transient-enhanced diffusion of arsenic beyond the end-of-range region between the As+ and Ge+ implanted and annealed samples was used to isolate the effects of arsenic clustering and precipitation. The results showed that point defects induced during clustering and/or precipitation did not contribute to the enhanced diffusion of arsenic although these defects did coalesce to form extended defects at the projected range. However, damage beyond the end-of-range region did cause enhanced diffusion of arsenic.

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