Leroy Chang

Leroy L. Chang (20 January 1936 – 10 August 2008) was an experimental physicist and solid state electronics researcher and engineer.

After Manchuria was occupied by Imperial Japan in 1931, his family escaped to inland China and Chang was born on 20 January 1936 in Kaifeng, Henan province.

His father was Zhang Shenfu (engineer), a well-known geologist and Republic of China official who was assassinated by the Communists in 1946.

His mother, Li Xiangheng, was one of the first group of women elected to the Legislative Yuan in 1948.

After moving to Taiwan, Chang studied electrical engineering at National Taiwan University, graduating in 1957.

He obtained his master's degree in 1961 at the University of South Carolina.

Born in China, he studied in Taiwan and then the United States, obtaining his doctorate from Stanford University in 1963.

As a research physicist he studied semiconductors for nearly 30 years at IBM's Thomas J. Watson Research Center, New York.

This period included pioneering work on superlattice heterostructures with Nobel Prize-winning physicist Leo Esaki.

His doctorate (PhD) in solid-state electronics and electrical engineering was awarded by Stanford University in 1963.

Between 1963 and 1992, with the exception of a sabbatical year, Chang worked at IBM's Thomas J. Watson Research Center, New York, USA.

He held the position of researcher for some 12 years (1963 to 1968; 1969 to 1975), with a sabbatical year as associate professor at the department of electrical engineering at the Massachusetts Institute of Technology (1968-9).

In the 1970s, he pioneered development of quantum well and superlattice structure (SLS) techniques.

One of the key results from Chang's work in this period was using molecular beam epitaxy to grow superlattice structures in semiconductors.

The impact of the research carried out in the 1970s by Chang and his colleagues, including Nobel Prize-winning Leo Esaki and Ray Tsu, was highlighted by IBM researchers Theis and Coufal in 2004:

"Leo Esaki, Ray Tsu, and Leroy Chang began to envision and investigate designed quantum structures — which are based on interfaces between lattice-matched compound semiconductors — early in the 1970s. Ever since, the study of electronic systems of minute dimensions has ranked among the most exciting areas of condensed-matter physics."

This research was described in a 1973 paper in Journal of Vacuum Science and Technology that was cited multiple times over the following years.

On his return to IBM research, he spent 9 years as manager of its Molecular Beam Epitaxy section (1975 to 1984).

Eleven years later, in 1984, this pioneering research paper was featured as a Citation Classic by ISI, an organisation that tracks and measures impact factor and citation frequency and volume for journals and individual research papers.

Commentary for this retrospective article was provided by Chang.

Awards received included the International Prize for New Materials (1985), the David Sarnoff Award (1990) and the Stuart Ballantine Medal (1993).

This was followed by 7 years as manager of the Quantum Structure section (1985 to 1992).

His research included semiconductor physics, low-dimensional electron systems, and nanostructures.

This was a new university, having been established in 1991.

In 1993, Chang moved from New York to Hong Kong, switching from industrial research into academia in anticipation of the 1997 transfer of the British colony to China.

He was among the first wave of recruits to the Hong Kong University of Science and Technology.

Over the following 14 years he helped build the university's reputation in his roles as dean of science, professor of physics, vice-president for academic affairs, and emeritus professor.

After 29 years at IBM, Chang moved from industrial research into academia, being appointed the first dean of science at Hong Kong University of Science and Technology (HKUST) in 1993.

Chang's departure from New York and arrival in Hong Kong in 1993 was part of a wider influx that saw many leading scientists and researchers taking up positions at universities and institutions in the British colony to be able to advantage of the opportunities presented by the 1997 transfer to Chinese control.

Quoted in an article in 1996, Chang stated:

From 1996 to 1998, he was president of the Hong Kong Institute of Science.

During and after this period, from 1997 until his retirement in 2001, he was also Professor of Physics and Electrical and Electronic Engineering at the university.

"I would never have come to Hong Kong if it was going to remain just a British colony. We came because of 1997."

In addition to his work at HKUST, Chang also supported other science and technology institutions in Hong Kong and the wider region.

Chang held the position of dean of science until 1998, when he became Vice President of Academic Affairs until stepping down from this role in 2000.

He retired in 2001.

Honours bestowed on Chang included membership of the US National Academy of Sciences, the Chinese Academy of Sciences, and Academia Sinica, the national academy of Taiwan.

Chang's death in 2008 was marked with memorial services, and a symposium in his memory was held the following year.

Leroy L. Chang's family was from Jiutai County, Jilin province in Northeastern China (Manchuria).

Chang's arrival was described in a 2011 account of the rise of this university: "Other recruits during the first decade included Leroy Chang, a world-renowned experimental physicist from International Business Machines (IBM)".