MaSSSoftech

Response.Redirect(path, "_blank", "menubar=0"); 
 
And add the below class 
 
public static class ResponseHelper 
{ 
public static void Redirect
(this HttpResponse response, string url, string target, string windowFeatures) 
{ 
if ((String.IsNullOrEmpty(target) || 
target.Equals("_self", StringComparison.OrdinalIgnoreCase)) && 
String.IsNullOrEmpty(windowFeatures)) 
{ response.Redirect(url); } 
else { Page page = (Page)HttpContext.Current.Handler; 
if (page == null) 
{ 
throw new InvalidOperationException(
"Cannot redirect to new window outside Page context."); } 
url = page.ResolveClientUrl(url); 
string script; 
if (!String.IsNullOrEmpty(windowFeatures)) 
{ script = @"window.open(""{0}"", ""{1}"", ""{2}"");"; } 
else { script = @"window.open(""{0}"", ""{1}"");"; } 
script = String.Format(script, url, target, windowFeatures); 
ScriptManager.RegisterStartupScript(page, typeof(Page), "Redirect", script, true); 
} } } 
 
 
OR
Use Java Script
ScriptManager.RegisterStartupScript(this.Page, typeof(Page), 
"Redirect", "window.open('Default.aspx', '_blank', 'menubar=0, width=906, 
height=550, scrollbars=1, status=0');", true);