654877bd_erials_Science_and_Engineering__Significance
[Date] 1952 [Candidate Moment] Nick Holonyak, Jr., develops the first practical visible-spectrum light-emitting diode (LED). [Significance] 
Marks the beginning of the use of III-V alloys in semiconductor devices, including heterojunctions and quantum well heterostructures.
Greatest Moments in Materials Science and Engineering
Significance