Влияние электромиграции на зарождение вакансионных островков на поверхности Si(100) при сублимации

By means of in situ ultrahigh vacuum reflection electron microscopy, the nucleation of vacancy islands on wide terraces of the Si(100) surface is investigated. The temperature dependence of the displacement of a vacancy island nucleation center is determined in the process of heating a sample with a dc electric current. On the basis of a theoretical model, the effective electric charge of addimers is estimated in the direction across dimer rows of the surface. The effective charge has a positive sign and does not exceed 15 units of the elementary charge in the temperature range of 1020–1120°C.

Эволюция микролунок на широких террасах поверхности Si(111) в процессе высокотемпературного отжига

We have investigated in situ the morphological transformation of the Si(111) surfaces with micro-pits at large terraces during high-temperature annealing at T = 1200–1400°C. Experimental observation of the micro-pits kinetic decay have been performed by means of ultrahigh vacuum reflection electron microscopy. Focused ion beam system have been used for micro-pits creation at Si(111) terraces of large size. We have found that kinetic of micro-pit decay processes is affected by two dimensional vacancy islands nucleation at the micro-pit bottom when the micro-pit reaches the critical lateral size. The simple theoretical model has been proposed for describing the changes of the lateral size of micro-pit. The temperature dependence of two-dimensional vacancy islands nucleation frequency at micro-pit bottom is found to be described by the activation energy of 4.1 ± 0.1 eV.

Formation of Two-Dimensional Islands on Si(111) Surface During Homoepitaxial Growth

The nucleation of two-dimensional Si islands has been studied by in situ ultrahigh vacuum reflection electron microscopy on extra-large (~ 10–100 μm) atomically flat terraces of Si(111) surface. The dependence of two-dimensional island concentration N2D on substrate temperature T and silicon deposition rate R is found to obey relation N2D ן Rχ exp(E2D/kT) with χ≈0.58 or 0.82 and E2D ≈ 1.77 eV or 1.02 eV on the Si(111) surface with (7×7) or (1×1) structure, respectively. The critical nucleus during the growth on the extra-large terraces is found to consist of i = 1 particle at T ~ 700°С, and the critical nucleus size increases to i = 7–10 on terraces with smaller width, which is caused by the competition between the 2D island nucleation and the interaction of adatoms with steps bordering the critical terrace

Electromigration of Silicon Adatoms on Silicon (111) Surface

Existence of adatom gradient concentration on surface between step bunches was shown under sublimation, homoepitaxial growth and near equilibrium conditions on silicon (111) surface at above 900 ºС by means of in situ ultrahigh vacuum reflection electron microscopy and ex situ atomic force microscopy. It is experimentally confirmed that adatom have negative (at 1 100 ºС) and positive (at 1 300 ºС) effective charge. We found out the sign of adatom effective charge independent on the supersaturation volume on the surface. On the hasement of experimental data we evaluated the effective charge of adatom at 1 280ºС; this quantity is placed between 0,07 ± 0,01 and 0,17 ± 0,02 of electron unit