Thermal emittance and response time measurements of a GaN photocathode

Bazarov, Ivan; Dunham, Bruce; Liu, Xianghong; Virgo, M.; Dabiran, A. M.; Hannon, Fay; Sayed, Hisham

doi:10.1063/1.3110075

Cited by 37 publications

(27 citation statements)

References 23 publications

(27 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[1][2][3][4][5][6][7] GaN is known as the third generation semiconductor after Si and GaAs. Negative electron affinity ͑NEA͒-based GaN photocathode has a superior performing high quantum efficiency ͑QE͒, low dark current, and concentrative emitting electron energy distribution.…”

mentioning

confidence: 99%

Influence of the p-type doping concentration on reflection-mode GaN photocathode

Wang

Chang

Ren

et al. 2011

Applied Physics Letters

View full text Add to dashboard Cite

Four different p-type doping GaN photocathodes are activated by Cs/O, and the quantum efficiency (QE) curves are obtained. According to the QE equation, the curves are fitted. Both the QE curves and the fitting results show that the optimal p-type doping concentration is at 1017 cm−3. The electron diffusion length and surface-electron escape probability can be balanced well at 1017 cm−3. To a certain degree, thick emission layer is conducive to improving the QE, which is more obvious with the long wavelength.

show abstract

mentioning

confidence: 99%

Influence of the p-type doping concentration on reflection-mode GaN photocathode

Wang

Chang

Ren

et al. 2011

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…This requirement increases the complexity, mass, and volume of the spectrometer in such applications. The recent progress in high-quantum-efficiency GaN photocathodes 7 and systematic study of temporal emission response with hot carrier relaxation mechanisms involved in GaN photocathodes 8 has established IIInitride photocathodes as a promising candidate for UV low signal photodetection. The small electron affinity of GaN allows the development of highquantum-efficiency negative-electron-affinity (NEA) photocathodes with significant advantages such as solar blindness, radiation hardness, and low noise.…”

Section: Introductionmentioning

confidence: 99%

Novel Cs-Free GaN Photocathodes

Tripathi

Bell

Nikzad

et al. 2011

Journal of Elec Materi

View full text Add to dashboard Cite

We report on a novel GaN photocathode structure that eliminates the use of Cs for photocathode activation. Development of such a photocathode structure promises reduced cost and complexity of the device, potentially with stable operation for a longer time. Device simulation studies suggest that deposition of Si delta-doped GaN on p-GaN templates induces sharp downward energy band bending at the surface, assisting in achieving effective negative electron affinity for GaN photocathodes without the use of Cs. A series of experiments has been performed to optimize the quality of the Si delta-doped layer to minimize the emission threshold of the device. This report includes significant observations relating the dependence of device properties such as emission threshold, quantum efficiency, and surface morphology on the Si incorporation in the Si delta-doped layer. An optimum Si incorporation has been observed to provide the minimum emission threshold of 4.1 eV for the discussed Cs-free GaN photocathodes. Photoemission (PE), atomic force microscopy (AFM), and secondary-ion mass spectroscopy (SIMS) have been performed to study the effect of growth conditions on device performance.

show abstract

“…These issues remain even though aggressive and substantial efforts have been undertaken to reduce the MTE that figures prominently in the emittance figure of merit. Efforts include minimizing uncorrelated emittance growth affected by space charge forces through beam shaping of the initial distribution 11 (thereby requiring photocathode response times smaller than a picosecond) 25 , increasing the pulse length so as to enable smaller laser spot sizes 26 , altering the degree of band bending at the surface of a semiconductor photocathode such as GaN so as to limit scattering effects and the randomization of momentum gain near the surface 26 , and controlling the surface roughness by improving the surface preparation procedures in III-V NEA photocathodes 27,28 .…”

Section: Introductionmentioning

confidence: 99%

Perspectives on Designer Photocathodes for X-ray Free-Electron Lasers: Influencing Emission Properties with Heterostructures and Nanoengineered Electronic States

et al. 2018

View full text Add to dashboard Cite

The development of photoemission electron sources to specifically address the competing and increasingly stringent requirements of advanced light sources such as X-ray Free Electron Lasers (XFELs) motivates a comprehensive material-centric approach that integrates predictive computational physics models, advanced nano-synthesis methods, and sophisticated surface science characterization with in situ correlated study of photoemission performance and properties. Related efforts in material science are adopting various forms of nanostructure (such as compositionally graded stoichiometry in heterostructured architectures, and quantum features) allowing for tailored electronic structure to control and enhance opto-electronic properties. These methods influence the mechanisms of photoemission (absorption, transport, and emission) but have not, as yet, been systematically considered for use in photocathode applications. Recent results and near-term opportunities are described to exploit controlled functionality of nanomaterials for photoemission. An overview of the requirements and status is also provided.

show abstract

Thermal emittance and response time measurements of a GaN photocathode

Cited by 37 publications

References 23 publications

Influence of the p-type doping concentration on reflection-mode GaN photocathode

Influence of the p-type doping concentration on reflection-mode GaN photocathode

Novel Cs-Free GaN Photocathodes

Perspectives on Designer Photocathodes for X-ray Free-Electron Lasers: Influencing Emission Properties with Heterostructures and Nanoengineered Electronic States

Contact Info

Product

Resources

About