LAUSR

High‐quality diamond intrinsic layer was epitaxially grown on a IIb‐type boron‐doped diamond substrate. The quality of the epitaxy layer was evaluated by Raman spectroscopy and cross‐polarizer images and compared with other samples. The dark current of the diode was analyzed, revealing a rectification ratio as high as 2 × 109 at ±7 V. Current‐voltage characteristics of the converter under the irradiation of different americium‐241 activity sources were investigated. A maximum total conversion efficiency (ηtotal) of 1.41%, short‐circuit current (Isc) of 6.68 nA/cm2, and open‐circuit voltage (Voc) of 1.06 V from the diamond alpha‐voltaic battery were obtained under the irradiation of an americium‐241 source with a source activity of 8.85 μCi/cm2. The trend for the battery parameters with the increase in the activity of the americium‐241 source was clarified. Parameters Isc and Voc increase with the increase in the radioactive source activity. The ηtotal increases with the increase in the source activity but fluctuates in a certain activity interval with an increase in the fill factor, and then decreases with the increase in radioactive source activity. The research results are significant for the design of nuclear batteries.