Metallurgical Junction
The metallurgical junction is that point in a PN junction where the n-region and the p-region meet. As you may infer, metallurgical junction and PN junction are essentially synonymous, though there may be people who will get annoyed due to some minor technicality. It’s interesting, though perhaps not overly important, to note that it’s called the metallurgical junction because the PN junction is created via a metallurgical process.