To check the first usage, I contacted Suntola himself. For certain, ALD Window has been presented in the 1989 review. However, according to Suntola it is likely that the term has been in use already in early 1980s. Below is an image which is probably a mid-step in the evolution towards the ALD window concept that we now know. It is from 1981 from Suntola's invited talk at the ICVGE-5 conference.
|Scanned slide from the invited presentation T. Suntola, "Atomic Layer Epitaxy", Tech. Digest of ICVGE-5, San Diego, 1981. Provided by Tuomo Suntola.
This describes the temperature dependency of Zn + S --> ZnS process. As the graph is presented for elemental reactants, part of the features of a typical ALD window graph are not present.
Those interested can find more info related to this particular talk in the "Suntola ALE essay", Chem. Vap. Deposition 20 (2014) 332-344. Although there were loud critics on the use of "epitaxy", this talk was important in the way that from it, ALD research in Japan got started through Nishizawa.