Glancing angle deposition of Ge nanorod arrays on Si patterned substrates

Abstract

A periodic arrangement of Ge nanorods on a Si(111) substrate was realized by glancing angle deposition (GLAD) onto honeycomb-like arranged Au hillocks formed using a self-assembled monolayer of polystyrene nanospheres as an evaporation mask. Additionally, a honeycomb-like arrangement of Au dots was used as an etch mask in a reactive ion beam etching process for pattern transfer procedure. Resulting honeycomb patterns consisting of Si hillocks within the Si(111) substrates were utilized to deposit Ge nanorods. Effective morphological variations in shape and dimension of GLAD-grown nanorods on honeycomb-like patterned substrates with both Au dot and Si dot arrays are strongly influenced by interseed distances, seed heights, and consequently shadowing lengths. For a large pattern period, it was observed that the usual triangular shape of the nanorod changed to a hexagonal shape as an effect of additional particle flux that reached the growing nanorod from the direction of second and third-nearest neighbors due to inadequate shadowing lengths and increased interseed condensation.

Perspectives on oblique angle deposition of thin films: From fundamentals to devices

“…SEM micrographs of different OAD layers on different patterned substrates, (b) Ta deposited on a substrate covered with packed nanospheres (nanosphere lithography deposition) [112], (c) hexagonal arrays of W deposited over two time periods on an Al lattice template produced by anodization [102], (d) hexagonal arrays of Ge deposited over increasing periods of time on a patterned gold substrate [105], and (e) Si nanostructures OAD deposited on a nanoimprinted substrate with periodic stepped and flat surfaces [106].…”

“…Expanding on this simple approach, the use of substrates with a well-defined lithographic pattern opens up a range of new and unexpected possibilities for the nano-structuring of OAD thin films. To this end, patterned substrates consisting of well-ordered nano-structured array patterns or seed layers have been prepared through a variety of lithographic methods, laser writing, embossing or other top-down fabrication methods [24,87,[98][99][100][101][102][103][104][105][106][107][108][109]. Among these, the use of colloidal lithography (i.e., OAD on a substrate pre-coated with packed nanospheres of different materials) has gained much popularity over the last few years thanks largely to its simplicity [110][111][112][113].…”

Synthesis of WO3 nanoblades by the dealloying of glancing angle deposited W-Fe nanocolumnar thin films

“…The glancing angle deposition (GLAD) method has attracted attention due to its relative simplicity and feasibility for fabricating sculptured porous nanostructured thin films [21]. Under GLAD conditions, the particle flux is incident to the substrate surface at an oblique angle β (β ⩾ 80°, as measured with respect to the substrate normal), and columnar nanostructures are formed due to the self-shadowing mechanism, without the need for any further processing steps [10,[21][22][23][24][25][26]. By utilizing different substrate rotation schemes, spirals, screws, vertical columns and chevrons can be grown [10,23].…”

Nanosphere lithography for device fabrication

“…15 NSL structures also act as catalysts for the growth of semiconductor nanowires, 4 and can initiate pillar formation in glancing angle deposition of films, among other examples. 16,17 Recently, we achieved the selective self-organization of spheres within a trench formed by optical lithography on a silicon wafer, using a doctor-blade-based NSL technique. 18,19 Sphere deposition can be largely suppressed by a self-assembled layer of octadecyltrichlorosilane molecules on the substrate top surface: see Figure 2(a).…”