We report on phosphorus diffusion and activation related phenomena in germanium. We have used both conventional thermal processing and laser annealing by pulsed nanosecond Nd:YAG laser. Chemical profiles were obtained by secondary-ion-mass spectroscopy, sheet resistance was estimated by the van der Pauw method, and structural defects were monitored by transmission electron microscopy. Our study covers the temperature range from 440 to 750 °C, and we were able to efficiently simulate the dopant profiles within that temperature range, taking into account a quadratic dependence of the P diffusion coefficient on the free electron concentration. To achieve that we have taken into account dopant activation dependence on temperature as well as dopant pile-up near the surface and dopant loss owing to outdiffusion during the annealing. A combined laser thermal treatment above the melting threshold prior to conventional annealing allowed the elimination of the implantation damage, so we could perceive the influence of defects on both transient dopant diffusion and outdiffusion.
We report arsenic and phosphorus diffusion experiments and activation related phenomena in codoped germanium substrates utilizing conventional thermal annealing. Chemical profiles were obtained by secondary ion mass spectroscopy, sheet resistance was estimated by the Van der Pauw method. Our study covers the temperature range from 600 to 750 °C. We accurately described the dopant profiles with a quadratic dependence of the dopants diffusion coefficient on the free electron concentration. In our simulations we considered the dopant pile-up near the surface and dopant loss owing to outdiffusion during the annealing. Although the double donor codoping technique exhibited no advantage over monodoping with P concerning the level of activation and junction depth, it was interesting to observe the different diffusion behavior of the two dopants. Whereas the diffusion of As indicates a retardation under codoping the diffusion of P remains either unaffected or is slightly enhanced by codoping. The activation level of the codoped samples remains lower compared to the respective monodoped samples, except for the highest annealing temperature.
In this work we perform a systematic study of the dissolution of a dislocation loop layer under the influence of inert SiO2∕Si and nitrogen-rich SiO2∕Si interfaces. The composition of the dislocation loop layer was just after its formation 10%–20% Frank dislocation loops and 90%–80% perfect prismatic loops. During subsequent inert (N2) ambient annealing the differences of the kinetics between the two loop populations have been studied as a function of the interface type. It has been shown that during the nonconservative Ostwald ripening process the defect band loses interstitials mainly due to the dissolution of perfect prismatic loops, while Frank loops remain almost unaffected by the presence of both interfaces. In parallel a competition between the interface and the population of Frank loops in absorbing the interstitials released by the prismatic loops took place. The nitrogen-rich SiO2∕Si interface has been proved in general a less effective interstitial sink than the common one and under specific annealing conditions less effective even than the small Frank loops population.
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