Leroy Chang

Leroy L. Chang
Born	(1936-01-20) 20 January 1936 Kaifeng, Henan, China
Died	10 August 2008(2008-08-10) (aged 72) California, USA
Occupation	Physicist
Years active	1963–2001
Known for	Research on semiconductor superlattices and quantum wells

Leroy L. Chang (; born 20 January 1936, died 10 August 2008) was a Taiwanese-American physicist specializing in experimental solid-state electronics. Originally from China, he pursued his education in Taiwan and the United States, culminating in a PhD from Stanford University in 1963. Chang dedicated nearly three decades to IBM's Thomas J. Watson Research Center, where he conducted pioneering research on superlattice heterostructures alongside Nobel Prize winner Leo Esaki.

In 1993, Chang shifted from industrial research to academia by joining the founding faculty of the Hong Kong University of Science and Technology (HKUST), established prior to Hong Kong’s 1997 sovereignty handover. Over a span of fourteen years, he significantly contributed to the university’s scientific development, serving as dean of science, professor of physics, vice-president for academic affairs, and later as emeritus professor until his retirement in 2001.

Chang held memberships in prestigious institutions including the US National Academy of Sciences, the Chinese Academy of Sciences, and Taiwan’s Academia Sinica. His accolades feature the International Prize for New Materials (1985), the David Sarnoff Award (1990), and the Stuart Ballantine Medal (1993). Following his death in 2008, memorial events and a dedicated symposium honored his legacy.

Early life and education

The Chang family hailed from Jiutai County, located in Jilin province of Northeast China. Due to the Japanese occupation of Manchuria beginning in 1931, they relocated inland, where Leroy L. Chang was born on 20 January 1936 in Kaifeng, Henan province. His father, Zhang Shenfu, was a distinguished geologist and official of the Republic of China who was assassinated in 1946. His mother, Li Xiangheng, became one of the earliest women elected to Taiwan’s Legislative Yuan in 1948.

After relocating to Taiwan, Chang obtained a bachelor's degree in electrical engineering from National Taiwan University in 1957. He then earned a master's degree at the University of South Carolina in 1961 before completing his doctorate in solid-state electronics and electrical engineering at Stanford University in 1963.

Industry, research and academia

From 1963 until 1992—with the exception of one sabbatical year—Chang was employed at IBM’s Thomas J. Watson Research Center in New York. His roles included researcher from 1963 to 1968 and again from 1969 to 1975; during the intervening year (1968–69), he served as an associate professor in MIT’s electrical engineering department. Upon returning to IBM, he led the Molecular Beam Epitaxy group (1975–1984) and later directed the Quantum Structure section (1985–1992). His investigations concentrated on semiconductor physics, low-dimensional electron systems (2DEG), and nanostructures within nanotechnology. Notably, during the 1970s he was instrumental in developing techniques involving quantum wells and superlattice structures.

One of Chang’s significant contributions involved employing molecular beam epitaxy to fabricate semiconductor superlattice structures—a breakthrough documented in a highly cited 1973 article published in Journal of Vacuum Science and Technology. This research was later honored as a Citation Classic by the Institute for Scientific Information (ISI) in 1984. Collaborating with Nobel laureate Leo Esaki and Ray Tsu (Raphael Tsu), Chang helped establish engineered quantum structures as a central field within condensed-matter physics.

Following almost three decades at IBM, Chang moved into academia as founding dean of science at HKUST in 1993. His appointment played a critical role in HKUST’s emergence as a leading research institution. He held the dean position until 1998 before becoming Vice President for Academic Affairs until 2000, simultaneously maintaining professorships in Physics and Electrical and Electronic Engineering until retiring in 2001. His relocation to Hong Kong aligned with a broader movement of prominent scientists attracted by opportunities associated with the upcoming transfer of sovereignty.

In addition to his work at HKUST, Chang actively participated in regional scientific development initiatives. He served as president of the Hong Kong Institute of Science from 1996 to 1998 and contributed significantly to establishing Taiwan’s Research Center for Applied Sciences (RCAS) under the auspices of Academia Sinica, where he was an advisory committee member. After retirement, he continued as an emeritus professor at HKUST until his passing.

Awards and honours

• 1984: Elected Fellow of the American Physical Society
• 1985: Recipient of the American Physical Society's International Prize for New Materials (shared with Leo Esaki and Raphael Tsu) in recognition of groundbreaking work on artificial semiconductor superlattices and their unique electronic characteristics.
• 1988: Inducted as a Member of the National Academy of Engineering for significant accomplishments in superlattice heterostructures.
• 1990: Named Fellow of the Institute of Electrical and Electronics Engineers owing to contributions to superlattices and semiconductor quantum wells.
• 1990: Awarded the IEEE's David Sarnoff Award for advancements in quantum wells and superlattice technologies.
• 1993: Honoured with the Franklin Institute's Stuart Ballantine Medal in Physics.
• 1994: Became a Member of the United States National Academy of Sciences.
• 1994: Selected as a Foreign Member of the Chinese Academy of Sciences, among its initial 14 international members.
• 1994: Designated Academician of Academia Sinica (Taiwan).
• 1994: Admitted to the Hong Kong Academy of Engineering Sciences.
• 1995: Conferred Honorary Doctor of Science (D.Sc.) degree by HKUST.

Death and tributes

Chang passed away on 10 August 2008 in California, USA. Memorial ceremonies took place at El Camino Memorial Park in San Diego and at the Hong Kong University of Science and Technology. In 2009, Academia Sinica organized a commemorative symposium entitled Recent Advances in Applied Sciences to celebrate his legacy. The event included dedications such as "A Tribute to Academician Leroy Chang" and "Remembering Leroy: from SL/QW to RCAS." Upon his death, HKUST colleagues, including founding president Chia-Wei Woo, expressed deep admiration for Chang’s commitment:

Leroy consistently exhibited enthusiasm and high spirits, combined with a logical and pragmatic approach, clarity and decisiveness, efficiency, and effectiveness – all enriched by his sharp wit and humor. As Dean of Science and Vice-President for Academic Affairs, he set aside his internationally acclaimed scientific career to selflessly foster a robust academic environment. The founding team at HKUST could not have wished for a more steadfast ally in establishing this institution. His loss is profoundly mourned.

Personal life

Chang’s daughter, Leslie T. Chang, is an accomplished author and journalist, married to Peter Hessler, renowned for his literary works about China.

External links

• Photograph of Leroy L. Chang (1) (Array of Contemporary American Physicists)
• Photograph of Leroy L. Chang (2) (National Academy of Engineering)
• Hetero-superlattice PN junctions (US Patent 5416337)
• Superlattice ultrasonic wave generator (US Patent 4469977)
• 1999 interview with Chang as Vice-President for Academic Affairs (HKUST)