Radiation detection system using solid-state detector devices
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.
1. A method of fabricating a neutron detection device, comprising:
pulverizing neutron reactive material to provide granules that have a high packing density when filling elongated tube cavities in an active region of a neutron detection semiconductor device, wherein a center to center distance between each elongated tube is between 5 and 20 microns;
bringing to a common electric potential
the pulverized neutron reactive material, and
a semiconductor wafer including elongated tube cavities extending from respective openings in a surface of an active region of a neutron detection semiconductor device being fabricated on the semiconductor wafer and continuing almost through, but not totally through, the active region, wherein the active region exhibits an internal electric field causing free charges to separate and drift across the active region; and
while maintaining the pulverized neutron reactive material and the semiconductor wafer at the common electric potential, filling the elongated tube cavities to a high packing density with the pulverized neutron reactive material.
2. The method of claim 1 , further comprising:
coating the surface of the active region, and including coating the pulverized neutron reactive material at the openings in the surface after the elongated tube cavities are filled, with a neutron reactive coating layer comprising Boron-10 mixed with a polymer base vehicle, the coating securely packing the neutron reactive material filling the elongated tube cavities to a high packing density.
3. The method of claim 1 , wherein the pulverized neutron reactive material filling the elongated tube cavities comprises Boron-10.
4. The method of claim 1 , wherein the pulverized neutron reactive material filling the elongated tube cavities comprises Boron-10 powder having granules of a mean diameter less than or equal to approximately 1 micron to provide a high packing density in the elongated tube cavities.
5. The method of claim 1 , wherein the neutron detection semiconductor device being fabricated on the semiconductor wafer comprises gallium arsenide or germanium; and
wherein the active region of the neutron detection semiconductor device respectively comprises a high purity gallium arsenide active region or a high purity germanium active region.