On my BB 9810, you could use the RFC to scan barcodes. Does the GS3 have this capability? I have not seen it. If not, do you need an app for it? If so, which one?
If you are on at&t, one of their apps available is a bar code scanner that also scans QR codes. There are also a few other free apps in the app store that do the same thing.
I use another called ShopSavvy at times, it's free.