SQL & PL/SQL :: How To Store Special Character In Database

i want to store special characters in database. i have tried following but not succeed. how to store and retrieve it. Herewith i'm posting my try.I want to store and retrieve following character.

SQL> select nchr(181) from dual;

N
-
µ

SQL> create table temp (uom varchar2(10));

Table created.

SQL> insert into temp values(nchr(181));

1 row created.

SQL> commit;

Commit complete.

SQL> select * from temp;

UOM
----------
?

here i'm getting the '?' but i want 'µ'.