Obtaining higher quantum efficiency and more stability has been an important developing direction in the investigation of GaAs photocathodes. By solving the one-dimensional diffusion equation for no-equilibrium minority carriers of reflection-mode GaAs photocathode materials, we can get the equations of the surface photovoltage curve before activation and the spectral response curve after activation for uniform and exponential doping GaAs materials. Through experiments and fitting calculations for two doping structural materials designed by us, the parameters of the body materials are exactly measured by the surface photovoltage curves, and the curves for surface escape probability are also accurately fitted by the comparative research before and after activation. The differences for the fitting results of two doping structures are also well analyzed. This comparative research can form a closed-loop research for GaAs photocathodes and will help us to deeply study the varied doping structures and optimize Cs-O activation technology for GaAs photocathodes in the future.
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http://dx.doi.org/10.1364/AO.50.004457 | DOI Listing |
The rapid development of GaAs photocathodes has led to an increased focus on the attainment of high quantum efficiency. Three types of exponential-doping structures with a high to low doping concentration distribution from the interior to the surface are proposed for reflective GaAs emission layers. These three structures generate different built-in electric fields that facilitate photoelectron emission.
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August 2024
School of Engineering, The Australian National University, Canberra, ACT 2600, Australia.
This study offers an in-depth examination of aluminum gallium arsenide (AlGaAs) as a high-performance and durable material for photoelectrochemical water splitting, a key method of cost-effective renewable hydrogen production. Purpose-designed pin-AlGaAs photocathodes are demonstrated to yield a remarkable photocurrent density of over 15 mA/cm and an impressive onset potential of 1.11 V vs RHE.
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November 2023
Univ. Lyon, CNRS, ECL, INSA Lyon, UCBL, CPE Lyon, INL, UMR 5270, 69130 Ecully, France.
Photoelectrochemical cells (PEC) are appealing devices for the production of renewable energy carriers. In this context, III-V semiconductors such as GaAs are very promising materials due to their tunable band gaps, which can be appropriately adjusted for sunlight harvesting. Because of the high cost of these semiconductors, the nanostructuring of the photoactive layer can help to improve the device efficiency as well as drastically reduce the amount of material needed.
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September 2022
Laboratory of Renewable Energy Science and Engineering, EPFL, Station 9, Lausanne 1015, Switzerland.
The practical implementation of photoelectrochemical devices for hydrogen generation is limited by their short lifetimes. Understanding the factors affecting the stability of the heterogeneous photoelectrodes is required to formulate degradation mitigation strategies. We developed a multiscale and multiphysics model to investigate and quantify the photostability of photoelectrodes.
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July 2022
Department of Physics & Astronomy, The University of Alabama in Huntsville, Huntsville, 35899, USA.
We present a theoretical model describing photoelectron transport dynamics in stepwise-doped GaAs photocathodes. Built-in electric field caused by the doping structure is analyzed, and the time-evolution of electron concentration in the active layer induced by a femtosecond laser pulse is solved. The predictions of the model show excellent agreement with the experimental data measured with pump-probe transient reflectometry, demonstrating the capability of the theoretical model in predicting photoelectron behaviors in real devices.
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