Patent ID: 8866152

Claim:
A betavoltaic device, comprising: an N+ doped semiconductor substrate having a top surface and a bottom surface and a thickness t N+ between the top and bottom surfaces, where t N+ is equal to or less than 100 micrometers (μm); an electrically conductive layer disposed immediately adjacent the bottom surface of the substrate; an N− doped epitaxial layer having a top surface, disposed immediately adjacent the top surface of the substrate; a P+ doped epitaxial layer having a top surface, disposed immediately adjacent the top surface of the N− doped epitaxial layer; an ohmic conductive layer having a top surface, disposed immediately adjacent the top surface of the P+ doped epitaxial layer; and a radioisotope layer disposed immediately adjacent the top surface of the ohmic conductive layer, wherein coincident regions of at least a portion of the radioisotope layer, the second electrically conductive layer, the P+ doped epitaxial layer, and the N− doped epitaxial layer, and the N+ doped substrate are etched so as to provide a plurality of devices including a common N+ doped substrate and first electrically conductive layer.