Solid state radiation detectors, such as neutron detectors and gamma ray detectors, have been proposed as alternatives to gas-tube based detectors. Radiation-detecting hetero-structures may be formed by using physical etching processes, such as reactive ion etching (RIE) to form trenches in a semiconductor substrate, followed by using chemical vapor deposition (CVD) to deposit radiation-detecting material within the formed trenches. However, RIE and CVD processes are quite complicated, requiring expensive specialized equipment, and can lead to poor fill ratios of radiation-detecting material. The methods of this disclosure electrophoretically deposit radiation-detecting particles into a plurality of cavities extending into a semiconductor substrate. These methods allow for high throughput formation of radiation-detecting structures, result in enhanced radiation detectors that contain a greater proportion of radiation-detecting material within the cavities, and simplify fabrication processing and improve yields by allowing room-temperature fabrication and avoidance of toxic process gases. Such radiation detectors could be used, for instance, to monitor illicit nuclear activities at ports, highways, business centers, etc., wherever deployment may be desirable to help promote national security.