Icon Inside a Gridview

Question

I'm trying to insert font awesome icon inside a gridview  but it  doesn't display anything 

when i click on that icon it should display selected row data as modal popup  

i am unable to insert this icon inside a grid view pls help me

<asp:TemplateField>
    <ItemTemplate>
    <button runat="server" id="btn" class="btn btn-mini" title="View" >
        <i class="fa-light fa-file"></i>
     </button>

    </ItemTemplate>
</asp:TemplateField>