I have read a lot of writers who are scientists, but I can't think of even one who's views could properly be considered 'scienticism'. Richard Dawkins comes as close as anyone, but even he admits that science can't answer every question. He has an enlightened disdain for Freud's psychological theories (which are empirically unprovable), but he doesn't reject the field of psychology or think it should be replaced with neurology.
I do know one person who's views might rightly be described as 'scientism'. But he isn't a scientist and in fact knows very little about science (though he is good at math). I think his 'scientism', though, boils down to a hatred for religion. He hates religion so much that I can't make an allusion from the Bible or quote a saying of the Buddha's without hearing his objection to such nonsense. He roundly rejects the existence of anything that cannot be seen, touched and measured precisely because this is the last refuge of religion now that science has so thoroughly refuted all of its claims about the origin of humans and cosmology.
Some lay people who don't understand science and have a chip on their shoulders when it comes to religion may very well be guilty of scientism, but I don't think they represent the mainstream in science. The late David Bohm wrote an extremely fascinating philosophical book, Wholeness and the Implicate Order. Roger Penrose and Douglass Hofstadter are at least two living scientists and writers who seem to be very comfortable with metaphysics. I'm certain there are plenty of others.