$ is not defined please help me...?

$ is not defined please help me...?

i have javascrit.js file
it contains code like below
I have jquery.js file also included in correct path but it shows $ not defined in document.ready function


document.write('<script src="jquery.js" TYPE="text/javascript"></script>');
 $(document).ready(function(){  
$('#bordercou').click(function() {
            
      alert("hai");
            });
});