How to set Document Expiration?

Hi friend's I want to set page expiration by clicking back button after log out..
Can anyone give me some reference i have used below code on page load but it does not work out...

  Response.Cache.SetExpires(DateTime.UtcNow.AddMinutes(-1));
        Response.Cache.SetCacheability(HttpCacheability.NoCache);
        Response.Cache.SetNoStore();