SBIR/STTR Phase II: A Semiconductor Device for Direct and Efficient Conversion of Radioisotope Energy

这个小型企业创新研究（SBIR）二期项目将制造一个四分之一硬币大小的倍他伏打电池原型。其目标是在不到半立方厘米的体积内利用氚化能源产生大约100微瓦的电力。该项目的第一阶段研究确定了构建半导体器件的可行性，该器件可直接有效地将放射性衰变释放的能量直接转换为电流。三维（3D）二极管是在大孔硅中通过沿所有孔壁放置p-n结来构建的。这些结形成了由分布在整个孔隙空间的气态氚（氢的放射性同位素，半衰期为12.3年）发射的β粒子（电子）的贝塔伏打转换层。这种新型三维几何结构的电流电压响应测量表明，与传统的二维平面二极管相比，效率提高了一个数量级。在三维二极管中，几乎每个衰变电子都进入了p-n转换层。第二阶段的研究重点将是提高3D二极管的性能，以最大限度地提高转换效率。此外，通过形成一种易于在孔隙空间中常规分散的氚化固体，源能量密度将显著增加。这项研究将导致实用核电池的发展。在商业上，倍他伏打电池可用于在许多难以到达的地点执行远程和长期任务的各种传感器和设备。这种核电池的成功商业化，其使用寿命的数量级增加，将大大增加自供电设备和传感器的利用率。将采取严格措施，确保这些核电池在开发、制造和商业化过程中的每一步的辐射安全。

This Small Business Innovation Research (SBIR) Phase II project will fabricate a prototype betavoltaic battery in a form factor the size of a quarter coin. The goal will be to generate approximately 100 microwatts of electrical power in a volume less than half a cubic centimeter from a tritiated energy source. Research conducted for the Phase I portion of this project established the feasibility of constructing a semiconductor device that directly and efficiently converts the energy released from radioactive decay directly into electric current. Three dimensional (3D) diodes were constructed in macroporous silicon by placing p-n junctions along the walls of all the pores. These junctions formed the betavoltaic conversion layer for beta particles (electrons) emitted by gaseous tritium (the radioisotope of hydrogen with a half life of 12.3 years) that was distributed throughout the pore space. Measurements of the current-voltage responses for this novel 3D geometry demonstrated an order of magnitude efficiency increase compared to conventional 2Dplanar diodes. In the 3D diode nearly every decay electron entered the p-n conversion layers. The focus of the Phase II research will be to enhance the performance of the 3D diodes to maximize conversion efficiency. Also, the source energy density will be increased markedly by developing a tritiated solid that can be easily and routinely dispersed in the pore space. This research will lead to the development of a practical nuclear battery. Commercially, betavoltaic batteries will be useful in a wide variety of sensors and devices used for remote and extended missions in many inaccessible locations. Successful commercialization of this nuclear battery with its order of magnitude increase in useful life is to increase significantly the utilization of self-powered devices and sensors. Stringent efforts will be made to ensure the radiological safety of these nuclear batteries at every step in the development, manufacturing and commercialization processes.