After long studies at his local library, Hall decided to attempt controlled experiments of his own with his mother's approval.
After working at Lockheed Aircraft as a tester, he returned to Caltech to finish up his studies and obtain his physics degree.
After four years at G.E., under the advice of Harper North, Hall obtained a Research Council Fellowship and returned to Caltech.
[3] While studying the characteristics of p-i-n diodes used as power rectifiers, Hall had a key insight, which resulted in his being co-credited with William Shockley and W. T. Read, Jr., for the analysis of nonradiative carrier recombination in semiconductors.
Hall developed the first semiconductor laser diode in 1962, while working at General Electric in Schenectady, New York.