helper to generate URL to "main url) with ID

How can I use the helper url() function to set an ID onto the "main" url of the application? I tried:

{!! url('', ['id' => Auth::user()->id]) !!}
{!! url('/', ['id' => Auth::user()->id]) !!}

Both doesn't work the way I need it to work, I get:

http://domain.com/13

I would need to get something like this:

http://domain.com/?id=13