json - Remove Escape character from object or string in c#?

I am passing string, through ajax, to action method in mvc,
Below is my ajax call

                $("#btnEncrypt").click(function () {
                var pay = JSON.stringify({
                  'payload': {"exp":1442515543,"method":"Login"},
                  'secretKey': "123456"
                });             

                $.ajax({
                type: "POST",                    
                url: '@Url.RouteUrl("GetData")',                   

                data: pay,
                contentType: 'application/json; charset=utf-8',
                success: function (data) {                        
                    alert("Success");
                },
                error: function () {
                    alert('error');
                }
                });
                }); 

Below is my Action method(Generate) in which I had pass two parameters

                [HttpPost]
                public ActionResult Generate(string payload, string secretKey)
                {
                 Here I am getting payload as "{\"exp\":1442515543,\"method\":\"Login\"}" 
                 instead of "{"exp":1442515543,"method":"Login"}"
                }

So, how can I get original request that I am passing through ajax call

    "{"exp":1442515543,"method":"Login"}" 

in action method without escaping character? Thank you in advance :)

Note :

1) I had tried without stringify for request parameter, but it's not worked.
2) Here parameters(exp and method) vary according to different request and I had around 200 request which all are using different paramters.

Answer

Here just need to Deserialize the payload at Action to remove escape charactor

var obj = new JavaScriptSerializer().Deserialize(payload,targetType:null);

Problem solved :)