By Mark Dwortzan
The North America MBE Advisory Board has selected Professor Theodore Moustakas (ECE) as the winner of its 2010 MBE Innovator Award. MBE stands for molecular beam epitaxy, a versatile and advanced thin-film growth technique used to make high-precision, pure compound semiconductor materials. The technique layers these materials one on top of the other to form transistors, lasers and other semiconductor devices used in fiber-optic, cellular, satellite and other applications.
The award recognizes Moustakas’ pioneering contributions in the development of MBE growth of nitride semiconductors and in the development of MBE-based optoelectronic devices. He’ll receive a $3,000 check from Veeco Instruments Inc. and a plaque from the North America MBE Advisory Board at the annual NAMBE Conference banquet in Breckenridge, Colorado on September 28.
“I am particularly excited that the scientific community has recognized my group’s contributions in the development of the new family of nitride semiconductors,” said Moustakas. “Researchers in both academia and industry are now investigating these materials because of their many potential applications.”
As Moustakas describes it, molecular beam epitaxy is a method of producing materials in the form of thin films, one that involves the reaction of beams of the constituent atoms on the top of a substrate, held at high temperatures in an ultra-high vacuum chamber. The ultra-high vacuum environment enables researchers to study the crystal structure and properties of the growing film in real time, making MBE an ideal method for the investigation and development of new materials.
The family of nitride semiconductors, which includes gallium nitride, aluminum nitride, indium nitride and their alloys, was discovered in 1970 at RCA Laboratories in an effort to develop light emitting diodes (LEDs) in the blue region of the electromagnetic spectrum. Moustakas started investigating this family of semiconductors when he joined Boston University in 1987, and employed the MBE method for their growth because the method is suitable for the study of new materials. As a result, he has since made several discoveries in both fundamental materials physics and device development.
In fundamental materials physics, Moustakas’ group’s breakthroughs include the first development of the nucleation processes required to grow nitride semiconductors on foreign, or non-nitride substrates. Intellectual property related to these processes was licensed to major manufacturers of blue LEDs and blue lasers. In device development, the group has achieved many firsts, including the discovery of how to form metal contacts to gallium nitride, a process required to fabricate any devices based on the semiconductor; the growth of the first blue LED by MBE; and the development of highly efficient, deep ultraviolet LEDs.
“These discoveries aided in the overall development of this class of semiconductors,” said Moustakas. “For example, blue-green LEDs are currently used for many applications including full-color outdoor displays, outdoor and automotive lighting, traffic lights, back lighting of displays and general illumination—including the replacement of existing light sources with LEDs with significant economic and environmental benefits. Blue lasers are used extensively for information storage, and UV LEDs are expected to find a number of germicidal applications such as water purification and air and surface sterilization.”