Rational Design and Passivation Strategy for Valid CdTe-Based Betavoltaic Cells

In this paper, cadmium telluride (CdTe) has been employed as the converter material to transduce β particles emitted by tritium (3H), with the aim of developing betavoltaic cells. The device structure was designed and the optimal thickness of CdTe film was determined using Monte Carlo simulation. The annealing process was carefully optimized with appropriate temperature and duration selected to reduce the dark current of the device to 1.31 × 10–12 A. Additionally, to improve the VOC of the device, a passivation layer of aluminum oxide (Al2O3) has been employed at the back surface of CdTe. The devices with the Al2O3 layer exhibit a median VOC of 196.5 mV, while those without Al2O3 only show a median VOC of 164 mV. The maximum VOC of the device reaches 224 mV. Detailed discussion confirms that the Al2O3 passivation layer can reduce the dark current and enhance the device performance. The origin of the relatively low ISC value is also analyzed.