Low-Temperature Growth of Cadmium Telluride (CdTe) Semiconductors on ASIC

Recent advances in synchrotron radiation sources have dramatically increased their brightness, resulting in ultra-high photon fluence with beam size approaching nanometers. Their high brilliance and coherence have enabled experiments with unprecedented resolution that were previously impossible. However, in order to truly benefit from these techniques, detectors for hard X-ray with energies >30 keV are a must. Several new high-Z semiconductors have been explored for high energy X-ray detectors, one of the best being cadmium zinc telluride (CZT) or cadmium telluride (CdTe) in its single-crystal format bump bonded to an ASIC. While these sensors have demonstrated the potential for high quantum detection efficiency and high spatial resolution, there are serious technical and economic challenges in fabricating large-area detectors with single crystals. We propose to address this issue with an alternative innovative technique. The proposed technique will overcome the challenges currently faced in bump-bonding semiconductors to the ASIC. Specifically, the Phase I goal is to demonstrate the feasibility of directly depositing high Z semiconductors on ASIC chips using RMD’s patent-pending, innovative, low-temperature deposition process. The proposed technique is low-cost and scalable, and will allow the desired thickness of the CdTe to be deposited over large area in an economical manner. Performance of the CdTe deposited ASIC will be evaluated and compared to that of current bump-bonded CZT sensors. The proposed developments will benefit numerous synchrotron-based studies, particularly applications that use hard X-rays >30 keV. The proposed technique for directly depositing high Z semiconductors on large area ASICs will dramatically lower the cost of detectors compared to the alternative technique of bump- bonding. Besides synchrotron-based applications, the proposed detector will have widespread use in practically all X-ray imaging applications. In particular, techniques such as high-energy X-ray tomography/diffraction that are widely used in medical and industrial imaging, homeland security, materials science, and nuclear physics studies will all benefit from the proposed research.