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Junghyun Park coauthored the indium tin oxide study with Xiaoge Liu and collaborators. Stanford's laboratory alumni page identifies Park as a former postdoctoral researcher.^[ref][ref]

The study's subject illustrates a useful modeling test. A parabolic conduction band has the form $E(k)={\hslash }^2{k}^2/(2m^{\ast })$ with constant effective mass. Adding an energy-dependent correction means that electrons occupying higher-energy states need not respond as though they have the same mass. Optical and transport behavior can then change together as the band fills. A model fitted at one carrier concentration should consequently be tested at others, rather than assuming its parameters remain constant.

By Xiaoge Liu, Junghyun Park, Ju-Hyung Kang, Hongtao Yuan, Yi Cui, Harold Hwang and Mark Brongersma. Applied Physics Letters 105, 181117 (2014). Figure 3: Hall measurements, carrier density, optical plasma frequency and mobility. Byline corroborated by Stanford SIMES: simes.stanford.edu/publications/quantum?page=21

Xiaoge Liu is the first-listed author of the 2014 study of band nonparabolicity and the optical properties of indium tin oxide. The Stanford laboratory's alumni record also identifies Liu as a former doctoral student.^[ref][ref]

The physical issue can be expressed through the Drude model relationwhere $n$ is carrier density and $m^{\ast }$ the relevant effective mass. If $m^{\ast }$ were fixed, doubling $n$ would double ${\omega }_p^2$. A density-dependent mass changes that prediction. Combining electrical and optical measurements can therefore test a band model rather than treating every shift in plasma frequency as a direct measure of carrier density alone.