Anomalous patterns and nearly defect-free ripples produced by bombarding silicon and germanium with a beam of gold ions

Abstract

We demonstrate that surface ripples with an exceptionally high degree of order can develop when germanium is bombarded with a broad beam of gold ions. In contrast, if silicon is sputtered with an Au− beam, patches of ripples with two distinct wave vectors can emerge. These types of order can be understood if the coupling between the surface morphology and composition is taken into account.

Self-organized nanopatterning of silicon surfaces by ion beam sputtering

“…Notably, a two-field theory for these ion-implanted systems can be developed, which is inspired by those available for IBS with concurrent deposition of impurities. Qualitative agreement with experiments is achieved [261].…”

“…For instance, use of metallic atoms as ions, rather than as impurities, can lead to interesting and novel patterns. Thus, irradiations with Au À ions at energies around 20 keV and at an incidence angle of 60 lead to a ripple pattern with a remarkable degree of order on Ge, and to a novel structure with ripple patches at oblique orientations, for the case of Si targets [261]. Notably, a two-field theory for these ion-implanted systems can be developed, which is inspired by those available for IBS with concurrent deposition of impurities.…”

Theory of nanoscale pattern formation produced by oblique-incidence ion bombardment of binary compounds

“…Well-ordered hexagonal arrays of nanoholes were the next new type of pattern to be discovered [3]. Very recently, it was shown how nonoverlapping patches of ripples at oblique angles to one another can be generated [56]. Clearly, the range of patterns that can be produced by bombardment with a broad ion beam is growing at an accelerating pace, further enhancing the prospects that ion sputtering will be widely adopted as a nanofabrication tool.…”

Producing virtually defect-free nanoscale ripples by ion bombardment of rocked solid surfaces

“…Unlike other methods [8,9], ours can be used to produce highly ordered surface ripples on an elemental material and does not require the implantation of an undesirable second atomic species or a high sample temperature. We also discussed how optimal values of the rocking frequency and the angles of incidence may be determined in an experiment.…”

“…A longstanding issue in this field, however, is the high density of defects in the patterns that typically form. This problem is the primary obstacle that prevents widespread use of ion bombardment as a nanofabrication tool, and much work has been done toward the goal of producing very well ordered patterns [2][3][4][5][6][7][8][9]. To date, no experiment has yielded highly ordered patterns on an elemental sample using a noble gas ion beam.…”