linq to ef select new data and convert to json fail

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LINQ

entity-framework

vaScriptSerializer js = new JavaScriptSerializer();
var temp1 = db.aaa.Join(db.bbb, t => SqlFunctions.StringConvert((decimal)t.id).Trim(), t1 => t1.id, (t, t1) => new
            {
                id = t.id,
                text = t.name,
                state = "closed",
                children = new
                {
                    id = t1.id + "1",
                    text = t1.text,
                },
            });
  return js.Serialize(temp1);

this is my linq code, i want use jquery tree generate tree menu in web page.but linq generated data is

[{"id": 1, "text": "1", "state": "closed","children": {"id": "11","text": "a"}}]

i want generate

[{"id": 1, "text": "1", "state": "closed","children": [{"id": "11","text": "a"}]}]

the json lost one pair of brackets in children node. i want to ask how to modify the linq code to generate right json.