Analysis of the attainable efficiency of a direct-bandgap betavoltaic element

• Main Authors: Sachenko, A. V, Shkrebtii, A. I, Korkishko, R. M, Kostylyov, V. P, Kulish, N. P, Sokolovskiy, I. O, Evstigneev, M
• Format: Journal Article
• Language: English
• Published: 13-04-2015
• Subjects: Physics - Materials Science
• DOI: 10.48550/arxiv.1504.03179

Conversion of energy of beta-particles into electric energy in a p-n junction
based on direct-bandgap semiconductors, such as GaAs, considering realistic
semiconductor system parameters is analyzed. An expression for the collection
coefficient, $Q$, of the electron-hole pairs generated by beta-electrons is
derived taking into account the existence of the dead layer. We show that the
collection coefficient of beta-electrons emitted by a \Tr-source to a GaAs p-n
junction is close to 1 in a broad range of electron lifetimes in the junction,
ranging from $10^{-9}$ to $10^{-7}$ s. For the combination \Pm/GaAs, $Q$ is
relatively large ($\ge 0.4$) only for quite long lifetimes (about $10^{-7}$ s)
and large thicknesses (about $100\,\mu$m) of GaAs p-n junctions. For realistic
lifetimes of minority carriers and their diffusion coefficients, the
open-circuit voltage realized due to the irradiation of a GaAs p-n junction by
beta-particles is obtained. The attainable beta-conversion efficiency $\eta$ in
the case of a \Tr/GaAs combination is found to exceed that of the \Pm/GaAs
combination.