Is this a borrowed chord?

Hello,

I wrote a riff in Em and I snuck in a chord or event that I can't explain. It sounds like it works, but I don't know what the function is if any.
Simplified, it's mostly dyads and power chords (e.g. Let Gmaj stand for G and B):

E5 / Gmaj / F#min / Emin / D5

But then I have a chord (low to high) : C#-G-B

Which moves to C-E-C and then B-D#-B.

I think I have a grasp on most of this, but how does the C#-G-B work? The C# works as a nice chromatic walk down from the D to the C and I know it's not in the key. If I were to throw a third into it, it would spell out a C#min7b5, but does that kind of chord typically bridge a VII and a VI (or two major chords for that matter?) Is it simply a borrowed chord that works or something else?

Thank You for your help!

You can take the key as being D Major; in that case C#-G-B would account for VII (m7; without 3rd); B-D#-B would for BVII ( a borrowed chord from G Major key) and the full progression being: II IV III II I ...VII BVII VI... ; i guess.

Greetings.



Edited 2 time(s). Last edit at 05/11/2018 01:38PM by Athair. (view changes)