How to send data in jQuery datatable?

My script is this

function Search(){
    var Searchterm = $('#Searchterm').val();
   $("#grid-selection").DataTable({            //my table id 
        "ajax": {
            "url": "Premium/Home/Search",     
            "type": "GET",
            "data": Searchterm,              //need to send this value to controller
            "contentType": "application/json; charset=utf-8",

            "datatype": "json"
        },
        "columns" : [
                { "data": "id", "autoWidth": true },
                { "data": "title", "autoWidth": true },
                { "data": "title", "autoWidth": true }
                //{ "data": "Country", "autoWidth": true },
                //{ "data": "City", "autoWidth": true },
                //{ "data": "PostalCode", "autoWidth": true }
        ]
 });
    }

And my controller code is like this

public JsonResult Search(string Searchterm)
{
}

The value of Searchterm passed to the controller is null. What is the right way to pass the value to the controller?