Most physics undergraduates will have encountered the potential well as their first problem in undergraduate quantum mechanics. New crystal growth technique such as molecular beam epitaxy has made it possible to produce quantum wells in practice. This sophisticated technology for the growth of high quality epitaxial layers of compound semiconductor materials on single crystal semiconductor substrates is becoming increasingly important for the development of the semiconductor electronics industry. in this article, I will review the main achievements of MBE both in fundamental research and manufacturing.