Effect of B–B impact ionization on GRPVC output: a semiconductor–nuclear physics interface

• Published in: Journal of physics. D, Applied physics Vol. 42; no. 13; pp. 135105 - 13510512
• Main Author: Liakos, John K
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 07.07.2009; Institute of Physics
• Subjects: Applied sciences; Energy; Exact sciences and technology; Natural energy; Photovoltaic conversion; Solar cells. Photoelectrochemical cells; Solar energy; Gamma radiation; Semiconductor materials; Conduction electron; Illumination; Impact ionization; Yield; Threshold energy; Interface; Photovoltaic cell
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/42/13/135105

We present calculations of efficiency, η, and open circuit voltage, V oc , of gamma ray photovoltaic cell (GRPVCs), in which impact ionization processes initiated by electrons in the conduction band (C-B) are taken into account. The contributions made to η and V oc by multiple e–h-pair production, caused by high energy γ-photons, are incorporated by summing up all possible higher order processes for given γ-photon energy. The discussion is divided into two types of impact ionization: (i) in type-I, pair creation by γ-photons and by subsequent photons due to electron impact are treated on an equal footing; (ii) in type-II the probability for impact ionization by electrons is a function of the γ-photon energy, and the latter is subject to constraints set by the energy threshold parameter Θ e . We find that for a GRPVC energy gap E g = 3.5 eV, and single e–h pair creation probability P e–h =0.8, driven by Th-229m1( E γ = variable, T 1/2 = 45 h)-like nuclear isomers, V oc reaches the maximum V ocmax = 2.7 V at η max ≈ 95% when E γ = 25 eV. In type-II processes the higher orders of e–h production do not make as high a contribution to η and V oc because of higher energy losses. Output power is also calculated for both types of processes and comparisons are made.