A neutron detection device (100) includes a semiconductor substrate including a gallium arsenide substrate region (102) having a back surface, and a high purity gallium arsenide active region (104) having a front surface. A back contact layer (118) is disposed on the back surface for providing a first voltage potential at the back surface. A plurality of elongated tube cavities extend from a plurality of respective openings in the front surface into the high purity gallium arsenide active region (104) and almost through, but not totally through, the high purity gallium arsenide active region (104). A front contact layer is disposed on the front surface for providing a second voltage potential at the front surface. Neutron reactive material, e.g., pulverized Boron-10 powder, fills the plurality of elongated tube cavities to a high packing density. A radiation detection system and a method of fabricating the neutron detection device are also disclosed.