High power density soft x-ray GaAs photodiodes with tailored spectral response
| Autor: | Dmitri Donetski, Kevin Kucharczyk, Jinghe Liu, Ricardo Lutchman, Steven Hulbert, Claudio Mazzoli, Christie Nelson, Boris Podobedov |
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| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Semiconductor Science and Technology. 37:085024 |
| ISSN: | 1361-6641 0268-1242 |
| Popis: | GaAs photodiode arrays have been designed for non-destructive monitoring of x-ray beam position in soft coherent beamline front ends in synchrotron light sources. A shallow p-on-n junction was employed to reduce the device photocurrent density to optimize the operation with beam power densities up to 20 W mm−2, mainly coming from hard x-rays. With this approach, the photocurrent is primarily defined by the excess carriers generated by low-energy x-ray photons absorbed near the detector surface. The p–n junction structures were grown by molecular beam epitaxy and processed into 64-element linear photodiode arrays. The devices were characterized first in the visible range with a high-power Ar-ion laser and then tested in the soft and hard x-ray regions up to 10 keV at two beamlines of the National Synchrotron Light Source II. The responsivity was measured to be 0.16 A W−1 at 0.7 keV and 0.05 A W−1 at 6 keV in agreement with modeling. At higher x-ray energies the measured responsivity was lower than predicted in the framework of the carrier diffusion model; a possible explanation is discussed. |
| Databáze: | OpenAIRE |
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