Experimental quantitative study into the effects of electromigration field moderation on step bunching instability development on Si(111)

Abstract

We experimentally studied the effects of a moderated electromigration field on the dynamics of the step bunching process on the Si(111) surface at 1130 • C (regime II) and 1270 • C (regime III). The surfaces with step bunch morphologies were created by annealing vicinal Si(111) at fixed temperatures while the applied electric field E was adjusted for every experiment. Scaling relations, y m ∼ h α E q , between the slope of a step bunch y m , step bunch height h, and electromigration field E were experimentally probed. Scaling exponents α ≈ 2/3 and q ≈ 1/3 were extracted from the step bunch morphologies created by annealing Si(111) in the regime III (1270 • C), which are in good agreement with the predictions of the generalized BCF theory. Scaling exponents α ≈ 3/5 and q ≈ 1/3 were extracted from the morphologies created by annealing in regime II (1130 • C). This result was compared to the scaling relations derived within the frame of the transparent step model, which correctly predicts the formation of the step bunching instability by step-up adatom electromigration. The scaling relation obtained by experiment was found to differ from the model predictions. We measured values of critical electric field (E cr), i.e., minimum electric field required for the step bunching to take place. A relatively weak field of E > 0.5 V/cm was found to be sufficient to initiate the step bunching process in regime II. This contrasts with regime III, where E cr = 1.0 and 2.0 V/cm were measured for Si miscut from the (111) plane by 1.1 • and 2.5 • , respectively. The increased values of E cr were attributed to the enhanced step-step repulsion in regime III. The theoretically predicted formation of compressed step density waves was observed upon annealing in both regimes with E < E cr .

Antiband instability on vicinal Si(111) under the condition of diffusion-limited sublimation

“…These step bunches grow with time and reach tens to hundreds of nanometers in height, while the terraces between them can grow to several micrometers in width. 1,2,10 Soon after the discovery of step bunching, it was found that prolonged dc annealing of Si(111) allows the surface morphology to further develop, giving rise to new morphologies such as antibands, which can be described as step bunches with slopes of the opposite sign as compared to the primary bunches. 11 Antibands are primarily formed via the shape evolution of atomic steps crossing the wide terraces between step bunches.…”

“…[1][2][3][4][5][6][7][8][9][10] When Si(111) is annealed by direct current (dc) driven along the miscut direction, adatom surface electromigration causes the atomic steps to gather together and creates step bunches separated by wide terraces. These step bunches grow with time and reach tens to hundreds of nanometers in height, while the terraces between them can grow to several micrometers in width.…”

Tuning magnetic anisotropies of Fe films on Si(111) substrate via direction variation of heating current

“…The step bunching due to heating by direct current has been well documented on the Si(111) surface with 1° miscut angle1516. It was observed that the step bunching was influenced by either annealing temperature or the direction of current flow.…”

“…The phenomenon that the variation of terrace width of Si(111) substrate with heating current direction can be explained by the surface electromigration of Si adatoms1516. The step bunching due to heating by direct current has been well documented on the Si(111) surface with 1° miscut angle1516.…”

“…Compared to metallic substrates, Si substrate is convenient to get a clean surface, and the surface morphology can be manipulated by different treating processes141516. Moreover, the magnetic nanostructures grown on the atomically flat Si(111) terraces have advantages in spintronic applications as a natural integration with Si-based semiconductor devices.…”