[Comparative study of uniform-doping and gradient-doping negative electron affinity GaN photocathodes]

Area of Science:

• Semiconductor Physics
• Materials Science

Context:

• Gallium Nitride (GaN) photocathodes are crucial for electron emission applications.
• Optimizing photocathode performance requires understanding doping structures and activation processes.
• External factors like annealing and Cs/O activation interact with internal material properties.

Purpose:

• To analyze the performance differences between uniform-doping and gradient-doping GaN photocathodes.
• To investigate the impact of doping structure on photocurrent during activation and quantum yield post-activation.
• To explain observed performance variations using a field-assisted photocathode emission model.

Summary:

• Gradient-doping GaN photocathodes exhibit a slower photocurrent growth rate and longer activation time but achieve higher quantum efficiency compared to uniform-doping counterparts.
• Experimental results indicate superior performance in gradient-doping structures after successful activation.
• The field-assisted photocathode emission model successfully explains these differences, highlighting the role of the built-in electric field.

Impact:

• The findings provide insights into designing high-performance GaN photocathodes for advanced applications.
• Gradient-doping offers a pathway to enhance electron emission probability and quantum efficiency.
• Understanding the interplay between doping, activation, and electric fields is key for future photocathode development.