planar film

https://doi.org/10.1351/goldbook.P04683
A
film
whose boundaries are represented by ideal parallel planes. The planar
film
thickness is defined as the distance between these planes. The terms nanometre
thick film
, micrometre
thick film
and millimetre
thick film
refer specifically to
film
thickness in the ranges 0.1100 nm, 0.1100 μm and 0.1100 mm, respectively.
Source:
PAC, 1994, 66, 1667. (Thin films including layers: terminology in relation to their preparation and characterization (IUPAC Recommendations 1994)) on page 1671 [Terms] [Paper]