Convert MARA data typee varchar to NVARCHAR for all fields

Hi,

I have to create models on MARA and MARC and to use the same in ABAP in HANA but ABAP doesnt support varchar so to change the same to NVARCHAR for many fields.

Can someone please tell me how to change the data type at the time of replication only in SLT?

Any detailed document with step by step approach will be very much helpful.

Thanks and regards

Sumeet