Direct deposition of GaN-based photocathodes on microchannel plates

Amir M. Dabiran; Andrew M. Wowchak; Peter P. Chow; Oswald H. W. Siegmund; Jeffrey S. Hull; James Malloy; Anton S. Tremsin

doi:10.1117/12.809503

6 February 2009 Direct deposition of GaN-based photocathodes on microchannel plates

Amir M. Dabiran, Andrew M. Wowchak, Peter P. Chow, Oswald H. W. Siegmund, Jeffrey S. Hull, James Malloy, Anton S. Tremsin

Author Affiliations +

Proceedings Volume 7212, Optical Components and Materials VI; 721213 (2009) https://doi.org/10.1117/12.809503
Event: SPIE OPTO: Integrated Optoelectronic Devices, 2009, San Jose, California, United States

Abstract

Epitaxial growth of p-type GaN-based UV photocathode by RF plasma assisted molecular beam epitaxy (MBE) on sapphire, fused silica, and alumina substrates was investigated. The electrical measurements indicted the growth of highly p-type GaN films as thin as 0.1 μm on c-plane sapphire with a thin AlN nucleation layer. Polycrystalline p-type GaN was obtained for growth on fused silica and alumina. Negative electron affinity (NEA) photocathodes were fabricated by cesium activation of the p-type GaN films in vacuum. Quantum efficiency for UV detection on different substrates was then characterized. To study the integration of UV photocathodes with MCPs, direct deposition of p-type GaN films on glass MCPs were done at low growth temperatures by MBE. The detection efficiency of polycrystalline p- GaN photocathodes in reflection mode was much less than the high quality p-type GaN films on sapphire, however, it was comparable to the detection efficiency of the latter measured in the semitransparent mode. This indicates the potential for fabrication of improved photocathodes with higher gain and better spatial and temporal resolutions.

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Amir M. Dabiran, Andrew M. Wowchak, Peter P. Chow, Oswald H. W. Siegmund, Jeffrey S. Hull, James Malloy, and Anton S. Tremsin "Direct deposition of GaN-based photocathodes on microchannel plates", Proc. SPIE 7212, Optical Components and Materials VI, 721213 (6 February 2009); https://doi.org/10.1117/12.809503

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