Print barcode that is smaller than 10mm x 8mm via ZPL

I am using ZPL to general a label for jewellery. I am trying to produce a barcode (likely Code 128) which would be smaller than 10mm x 8mm.

The best I can do is about twice the width:

^CF0,30

^FO48,94

^A0N,20,20

^BY1,3

^BCN,40

^FD12345678^FS

Any advice?

Regards,

Darcy