ASP.Net yeni POP-UP pencere açma c#

public void PencereAc(Page p_sayfa,string p_text)
{
string _value="<"+"script language='javascript'"+">window.open('"+ p_text +"', 'newwindow','width=500, height=400,left=300,top=300,toolbar=no, menubar=no, scrollbars=no, resizable=no');<"+"/script"+">";
p_sayfa.RegisterStartupScript("BenimKey", _value);