Gold-decorated highly ordered self-organized grating-like nanostructures on Ge surface: Kelvin probe force microscopy and conductive atomic force microscopy studies

Abstract

Nanoarchitecture by atomic manipulation is considered to be one of the emerging trends in advanced functional materials. It has a gamut of applications to offer in nanoelectronics, chemical sensing, and nanobiological science. In particular, highly ordered one-dimensional semiconductor nanostructures fabricated by self-organization methods are in high demand for their high aspect ratios and large number of applications. An efficient way of fabricating semiconductor nanostructures is by molecular beam epitaxy, where atoms are added to a crystalline surface at an elevated temperature during growth, yielding the desired structures in a self-assembled manner. In this article, we offer a room temperature process, in which atoms are sputtered away by ion impacts. Using gold ion implantation, the present study reports on the formation of highly ordered self-organized long grating-like nanostructures, with grooves between them, on a germanium surface. The ridges of the patterns are shown to have flower-like protruding nanostructures, which are mostly decorated by gold atoms. By employing local probe microscopic techniques like Kelvin probe force microscopy and conductive atomic force microscopy, we observe a spatial variation in the work function and different nanoscale electrical conductivity on the ridges of the patterns and the grooves between them, which can be attributed to gold atom decorated ridges. Thus, the architecture presented offers the advantage of using the patterned germanium substrates as periodic arrays of conducting ridges and poorly conducting grooves between them.

Site‐Specific Emulation of Neuronal Synaptic Behavior in Au Nanoparticle‐Decorated Self‐Organized TiOx Surface

“…Gold nanostructure-decorated pattern ridges are also observed in case of Au-ion induced patterned Ge surfaces at an oblique incidence. [36] In an attempt to analyze the surface topography of TiO x surfaces, we have carried out AFM measurements. Figure S3a, Supporting Information shows the AFM topographic image of an asgrown TiO x thin film (named as T0), revealing its uniform granular nature.…”

“…[3] On another note, ion implantation is also considered to be an extremely useful technique not only to modulate post-growth defect density within the switching medium [30] but also to give rise to self-organized pattern formation on its surface, depending on the ion-energy, -fluence, and incident angle. [30,32] As a result, anisotropic, electrical, [36] magnetic, [37,38] and optical properties [39,40] are realized. In addition, patterned surfaces are promising for cold cathode electron emission, [41,42] biology [43] as well as nano bio-electronic applications.…”

Surface nanopatterning by ion beam irradiation: compositional effects

“…Other examples of this type of patterning are those of Si and Ge surfaces irradiated with an Au + ion beam [140][141][142]. In the work by Mollick et al, Au + ions were used on the Si or Ge surfaces with an incidence angle θ = 60 • .…”

The role of incidence angle in the morphology evolution of Ge surfaces irradiated by medium-energy Au ions

“…The development of nanotopography on an initially flat surface under irradiation with a broad or focused ion beam of energy in the range of hundreds of eV to tens of keV is a self-organized process that has been often observed in metals, insulators and semiconductors [1,2]. By changing the physical and geometrical irradiation parameters, different types of patterns with different degree of regularity have been obtained, especially on semiconductor surfaces, such as arrays of nanodots by Au ion irradiation has been reported [8,9]; it shows highly regular ripples of a few hundred nanometer period decorated with a forest of curled nanowires of a few tens of nanometersize, ending with Au-rich nanoparticles.…”

“…Therefore, it is evident that the role of compositional heterogeneity is still an open, widely debated topic, where several ion-induced effects can play a role, and more theoretical and experimental studies are needed [16]. In this context, a particularly fascinating experimental result concerns the cited highly regular multiscale ripples on a Ge surface irradiated by Au atoms [8], where the fraction of implanted Au atoms can be intended as the second atomic species altering the surface composition [9]. The obtained results have been already discussed in the frame of the model considering the coupling of surface morphology and composition [35].…”