Examining the GaN Photocorrosion Potential for Stable Chemical Energy Storage

Wednesday, 4 October 2017: 18:20
Camellia 2 (Gaylord National Resort and Convention Center)
D. R. Baker (U.S. Army Research Laboratory)
Some of the most promising materials for photoelectrochemical water splitting are III-V semiconductors due to their high photoelectrochemical efficiency, and their inherent band positions with respect to the water splitting reactions. However, one of the primary detractors from their widespread use is their short lifetimes due to photocorrosion. GaN is an example of this as it readily photcorrodes in both acidic and basic aqueous media, though in dark environments it is stable. An electrochemical understanding of the corrosion reaction is imperative, but the traditional potentiodynamic analysis to determine corrosion potentials is impaired by the masking of photogenerated holes by the photocurrent of the solar cell. This talk presents how Mott-Schottky analysis can alternatively be used to find the photocorrosion potential of GaN, and how it relates to previously calculated surface properties of c-plane GaN. Using the newly found photocorrosion potential and mechanism several passivation methods, such as ALD and hole scavenging, are investigated to minimize the corrosion mechanism. Additional characterization techniques such as AFM and SEM are used to probe the corrosion mechanism and observe the effectiveness of passivation methods. The information found from this analysis will allow new materials to be designed which are inherently resistant to photocorrosion without the need for expensive and intensive surface passivation modifications.