Alfred Y. Cho

Alfred Y. Cho
Alfred Y. Cho
"Father" of the molecular beam epitaxy (MBE) method for producing novel layered materials used in wireless and optical communications, lasers, and transistors.

Beginning in the 1970's, Alfred Y. Cho produced a series of firsts in the highly competitive field of semiconductor devices. He is recognized as the coinventor and principal devloper of molecular beam epitaxy (MBE), a process in which materials are layered atop one another — atom by atom within a vacuum — with great precision to form electronic and photonic devices.

MBE led to radically new devices including high-speed transistors, microwave devices, laser diodes, and detectors. Most of the semiconductor lasers used in today's compact disc music players and DVD players are manufactures used MBE-grown material. MBE is also used to produce the Hall sensors found in disk drive speed controllers for computers and recorders. High electron mobility transistors (HEMTs), which are utilized as high-speed circuit components and in high-frequency, low-noise, direct-broadcast satellite and wireless communications, are manufactured using MBE. RFMD manufactures more than 500 million chips per year with MBE for power amplifiers and radio frequency switches used in mobile phones and global positioning systems.

The impact of MBE on fundamental science was as dramatic as its impact on semiconductor technology. The discovery of an entirely new state of electrons, the fractional quantized Hall Effect, was made possible as a result of MBE crystal quality. In 1994, Cho and coworkers demonstrated a fundamentally new type of laser that is a unipolar intersubband semiconductor laser called the quantum cascase (QC) laser. A significant ongoing contribution of MBE is the experimental generation of low dimensional systems.

Cho retired in 2001 after serving in the role of Semiconductor Research Vice President of Bell Laboratories, Lucent Technologies for 11 years, concluding a 33-year career of progressive leadership in research within the organization. He has authored more than 630 papers in surface physics, crystal growth, and device physics and performance. He holds 85 patents on crystal growth and semiconductor devices related to MBE.

Among Cho's many awards are the University of Illinois Alumni Achievement Award, National Medal of Science, National Medal of Technology, National Inventors Hall of Fame, IEEE Medal of Honor, C&C (Computer and Communication) Prize from Japan, and the first International Nanotechnology Prize (RUSNANOPRIZE) from Russia. Cho is a member of the National Academy of Engineering, National Academy of Sciences, American Academy of Arts and Sciences, Chinese Academy of Sciences, Third World Academy of Sciences, and Academia Sinica in Taiwan. He is also a member of the American Philosophical Society. 


  • BS, Electrical Engineering, 1960
  • MS, Electrical Engineering, 1961
  • PHD, Electrical Engineering, 1968
  • Doctor of Engineering Honorary Degree, 1973