Template-induced formation of α-W and size-dependent properties of tungsten thin films

Growth and characterization of sodium–tungsten oxide nanobelts with U-shape cross section

“…In our case, due to presence of the (2 1 1) plane in the spectrum, the crystalline structure of the ''as deposited'' film is identified as b-W phase with the equilibrium bcc structure. It is important to note that for low film thicknesses, the b-W phase is the favorable state [10]. According to the Debye-Scherrer equation, the crystalline size of the tungsten film was measured about 20 nm.…”

On‐Demand Preparation of α‐Phase‐Dominated Tungsten Films for Highly Qualified Thermal Reflectors

“…However, the physical properties of W films are phase dependent. Since there are generally two phases involved in W films, i.e., thermodynamically stable α phase with body‐centered cubic (bcc) lattice structure and metastable β phase (A15 crystal structure) . Thus, from the point of view of meeting diverse needs, how to achieve the on‐demand preparation of the α‐ or β‐W film is an important scientific issue.…”

“…With superior densification, magnetron sputtering is more popular for depositing W films. Nevertheless, concerning the on‐demand fabrication of α‐W films, some harsh conditions such as very low base pressure, purified sputtering gas, minimal residual oxygen, and intended substrate heating are always involved . For instance, the presence of trace oxygen is in favor of inducing nucleation of β‐W, meaning that ultrahigh base pressure is necessary to prepare α‐W films in order to shake off the influence of oxygen remnant .…”

“…For instance, the presence of trace oxygen is in favor of inducing nucleation of β‐W, meaning that ultrahigh base pressure is necessary to prepare α‐W films in order to shake off the influence of oxygen remnant . Predeposition of Mo or Cr seed layer is also effective to induce the formation of α‐W phase, but it makes the preparation more complicated. Another example is to fabricate α‐phase dominated W films utilizing DC‐bias assisted inductively‐coupled ionized sputtering .…”

“…Another example is to fabricate α‐phase dominated W films utilizing DC‐bias assisted inductively‐coupled ionized sputtering . However, on one hand, conductive substrates are needed; on the other, there is usually about 40 nm or even thicker β‐W incubation layer before the α‐W formation . In addition, although as‐deposited β‐W films could be transformed into α‐W counterparts after high temperature postannealing, notable surface coarsening generally happened .…”