Technology Commercialization and Partnerships | BSA 12-24: Wafer-Fused Semiconductor Radiation Detector

Category: electronics & instrumentation

BSA 12-24: Wafer-Fused Semiconductor Radiation Detector

BNL Reference Number: BSA 12-24

Patent Status: U.S. Patent Number 6,350,989 was issued on February 26, 2002

Summary

Wafer-fused semiconductor radiation detector useful for gamma-ray and x-ray spectrometers and imaging systems. The detector is fabricated using wafer fusion to insert an electrically conductive grid, typically comprising a metal, between two solid semiconductor pieces, one having a cathode (negative electrode) and the other having an anode (positive electrode). The wafer fused semiconductor radiation detector functions like the commonly used Frisch grid radiation detector, in which an electrically conductive grid is inserted in high vacuum between the cathode and the anode.

Description

By using wafer fusion, it is possible to put an electrically conductive grid between two semiconductors and bond them together to make the present invention, which is a waferfused semiconductor radiation detector (WAFUSRAD), and which is a direct analog of a Frisch grid gas detector, but using semiconductor materials and the wafer bonding technology. The wafer-fused semiconductor radiation detector can be fabricated using the same or two different semiconductor materials of different sizes and of the same or different thicknesses; and it may utilize a wide range of metals, or other electrically conducting materials, to form the grid, to optimize the detector performance, without being constrained by structural dissimilarity of the individual parts. The wafer-fused detector is basically formed, for example, by etching spaced grooves across one end of one of two pieces of semiconductor materials, partially filling the grooves with a selected electrical conductor which forms a grid electrode, and then fusing the grooved end of the one semiconductor piece to an end of the other semiconductor piece with a cathode and an anode being formed on opposite ends of the semiconductor pieces.

Benefits

The WAFUSRAD provides uperior energy resolution and radiation detection efficiency by largely removing imperfections of the previously known semiconductor-based electron-only devices, including dead regions created by the grid where no signal can be detected and decreased measurement volume wich result in decreased detection efficiency and non-uniform electric fields which cause variation in the charge collection time of the electrons and variation of the signal strength with the position of the x-ray and gamma-ray absorption event, resulting in decreased energy resolution.

Applications and Industries

Semiconductor radiation detectors are now used in a large variety of fields, including nuclear physics, X-ray and gamma ray astronomy, and nuclear medicine. Their imaging capabilities, good energy resolution, and the ability to fabricate compact systems are very attractive features, in comparison with other types of detectors, such as gas detectors and scintillators. Medical, imaging, nuclear nonproliferation, non-destructive detection, radiation imaging, and homeland security applications.