Performance degradation in GaSb thermophotovoltaic cells under proton and electron irradiations

Abstract

This study reports on the proton and electron irradiation-induced performance degradation in GaSb thermophotovoltaic cells. GaSb cells and GaSb single crystals were irradiated using 100 MeV and 100 keV protons and 1 MeV electrons. Through measurement of cells and single crystals and simulation of irradiation experiments, it is found that 100 MeV protons penetrate the whole GaSb cell and produce uniformly distributed irradiation damage in the functional layer of the cell, and the maximum power (P_MAX) of the cell decreases to 69 % when the proton fluence reaches 1 × 10¹² p/cm². 100 keV protons are mainly injected in the PN junction region of the cell, and when the fluence is 3 × 10¹¹ p/cm², the P_MAX decreases to ∼10 %, and the cell basically fails completely. 1 MeV electrons penetrate the PN junction region to reach the base area, and more than 95 % of the electron energy is deposited inside the cell, and the P_MAX decreases to 63 % when the electron fluence reaches 1 × 10¹⁶ e/cm². Proton and electron irradiations did not lead to significant structural damage in GaSb single crystals, but probably introduced Ga vacancies or vacancy cluster, which act as non-radiative recombination centres, reducing the carrier lifetime and concentration in the PN junction region of the GaSb cell, leading to degradation of its performance. This study informs the application of GaSb cells in radioisotope thermophotovoltaic systems.