Cs-free N-polar III-nitride photocathode detectors with high quantum efficiency: role of impurity incorporation at interfaces and planes

Emma Rocco; Kasey Hogan; Vincent Meyers; Ben McEwen; Lloyd Douglas Bell; F. Shadi Shahedipour-Sandvik

doi:10.1117/12.2578627

5 March 2021 Cs-free N-polar III-nitride photocathode detectors with high quantum efficiency: role of impurity incorporation at interfaces and planes

Emma Rocco, Kasey Hogan, Vincent Meyers, Ben McEwen, Lloyd Douglas Bell, F. Shadi Shahedipour-Sandvik

Author Affiliations +

Proceedings Volume 11686, Gallium Nitride Materials and Devices XVI; 116861B (2021) https://doi.org/10.1117/12.2578627
Event: SPIE OPTO, 2021, Online Only

Abstract

We report here our latest results of achieving high quantum efficiency (QE) N-polar GaN photocathodes through engineering of bulk and interfacial impurity concentrations. The photocathode structures studied consist of an N-polar p-GaN absorbing layer with 10 nm u-GaN cap layer. An increase in QE from 0.27% to 10.1% is observed for photocathodes grown without a regrowth interface between p-GaN and u-GaN cap layers compared to an identical structure with a regrown interface. SIMS is used to identify impurities at the regrowth interface, which cause lower QE due to scattering and modification of the electric field. The QE is further increased to 26.6% through a 2x increase in hole concentration when the structure is grown on a high hillock density template. This work demonstrates a combined approach that has the promise of advancing toward and surpassing performance of current state-of-the-art photocathodes in the UV range.

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Citation Download Citation

Emma Rocco, Kasey Hogan, Vincent Meyers, Ben McEwen, Lloyd Douglas Bell, and F. Shadi Shahedipour-Sandvik "Cs-free N-polar III-nitride photocathode detectors with high quantum efficiency: role of impurity incorporation at interfaces and planes", Proc. SPIE 11686, Gallium Nitride Materials and Devices XVI, 116861B (5 March 2021); https://doi.org/10.1117/12.2578627

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