DTR27BZ02-NV006 — Domestic Scalable Growth Of Large-Format Pixelated CZT Crystals For Advanced Radiation Detection

DTRA seeks to establish reliable, scalable, and secure domestic sources and fabrication processes for large-format monolithic cadmium zinc telluride (CZT) single crystals in the 44 × 44 × 15 mm form factor, optimized for pixelated electrode structures that enable high-performance room-temperature 3D position-sensitive gamma-ray imaging and spectroscopy. These crystals are essential for next-generation compact radiation detection systems supporting WMD detection, nuclear forensics, and other radiation detection efforts within the Department of War (DoW).

Compact, high-resolution, room-temperature gamma imaging and spectroscopy systems are critical for a number of government agency applications (DoW, DTRA, DOE/NNSA, IAEA, DHS), in addition to a number of commercial applications (nuclear power, medical community). CZT-based 3D position-sensitive detectors provide these capabilities without cryogenic cooling, leveraging the small-pixel effect and depth-of-interaction (DOI) sensing via pixelated anodes and timing readout. Current advanced systems rely on high-quality pixelated CZT, but most commercial modules use smaller crystals (~20–22 mm lateral dimensions). Furthermore, finished crystals with a thickness of around 5 mm are readily available for medical imaging; however, thicker crystals are often available from manufacturers by long-lead, custom order. Scaling to monolithic 44 × 44 × 15 mm crystals would significantly increase intrinsic efficiency (particularly for higher-energy gamma rays), reduce the number of crystals and interfaces per imager, improve geometrical coverage, simplify module assembly, and lower overall system complexity while maintaining or exceeding energy resolution targets of <1% FWHM at 662 keV. High-performance spectrometer-grade CZT at this scale is currently supplied primarily by a limited number of foreign or foreign-owned sources, creating recognized supply-chain vulnerabilities for critical national security radiation detection hardware. Tellurium feedstock is heavily concentrated overseas, and domestic high-end crystal growth capacity remains limited. Zinc and Tellurium are identified in the U.S. Geological Survey (USGS) 2025 List of Critical Minerals. Additionally, Executive Order 14415 "Securing America's Defense Supply Chains and Ensuring Domestic Acquisition of Critical Materials" (July 20, 2026), and related DoW supply chain initiatives, emphasize the need to strengthen domestic reliance on critical materials and components. This topic directly addresses that gap by focusing on domestic crystal growth and machining innovation—including process improvements to the Traveling Heater Method (THM), Accelerated Crucible Rotation Technique (ACRT)-enhanced methods, alternative or hybrid growth techniques, in-situ monitoring, and stoichiometry/defect control—capable of delivering the required size, uniformity, and spectroscopic performance at scalable yield and cost. Successful development will strengthen U.S. supply chain resilience while accelerating technology transition to operational systems. A successful development under this topic should result in CZT material freely available on the commercial market rather than for exclusive or limited use by license or other restrictions. Furthermore, it is not the intent of this topic to develop detector systems utilizing CZT. The solution must meet the following minimum specifications: Crystal Form Factor: Monolithic single-crystal CZT, nominal dimensions up to 44 × 44 × 15 mm (or equivalent large-format), suitable for pixelation with approximately 22 × 22 pixel anode contact matrix at ~2 mm pitch, a single cathode contact, and a guard ring contact around the edge of each. Material Quality: High spatial uniformity of carrier transport properties (electron μτ and adequate hole properties) across the full crystal volume; low defect density (e.g., Tellurium inclusions, grain boundaries, twins, etc.) sufficient to support high-performance spectroscopic operation; and low current leakage. Performance Target: Demonstrated or projected capability to achieve < 1% FWHM energy resolution at 662 keV when configured with pixelated readout and DOI sensing in a representative detector geometry. Domestic Production: U.S.-based growth process with clear, documented path to scalable yield, lot-to-lot reproducibility, and cost reduction; primary use of U.S. or allied-nation sourced raw materials with traceability. Validation: Precursor and crystal lots must be validated through non-destructive characterization (e.g., IR transmission, X-ray topography, μτ mapping) and, where feasible, proxy electrode testing or delivery to a qualified detector fabricator for performance assessment. Cost: Demonstrate that under high volume production cost per crystal volume is competitive with CZT commercially available from other commercial vendors. Objective specifications (desired but not required for basic consideration): Larger or thicker monolithic crystals (e.g., approaching 50 × 50 × 20 mm) with maintained uniformity. Demonstrated full pixelated detector performance meeting or exceeding < 0.8% FWHM at 662 keV in 3D configuration. Production-scale batches (multiple crystals per run) with ≥ 70% single-crystal yield meeting all quality metrics. Cost-competitive pathway versus current foreign-sourced material at equivalent performance. Extensibility to related materials or detector architectures (e.g., array tiling, alternative electrode designs).

Conceptualizing approach and proof-of-principle fabrication process. In Phase I, offerors shall perform a thorough assessment of current domestic and allied CZT crystal growth capabilities relevant to large-format detector-grade material. This assessment shall include market research on raw material (tellurium, cadmium, zinc) sourcing, identification of viable U.S. and/or allied feedstock pathways, and an analysis of alternative growth methods capable of achieving the target 44 × 44 × 15 mm form factor with required uniformity, including a technical risk analysis for each. Following the assessment, a specific technical approach and growth process shall be selected. A crystal growth and machining process shall be designed and demonstrated, producing at least one crystal (or multiple smaller proxy crystals demonstrating scalability) approaching the target dimensions with acceptable uniformity and performance. The process must demonstrate control of stoichiometry, defect density, and carrier transport properties. Offerors are encouraged to seek collaborations in areas outside of their expertise if needed to reach specifications; for example, crystals may be shipped to a partner for properties characterization and validation. The Phase I final report shall include: Detailed supply-chain and market assessment with identified domestic raw material sources, gaps, and risk mitigation strategies. Technical rationale for chosen growth method(s), supported by modeling, simulation, or literature where applicable. Detailed description of the developed growth and process control methodology. Non-destructive characterization results (e.g., IR transmission mapping, X-ray topography or equivalent, μτ property mapping) demonstrating spatial uniformity across the crystal volume. Proxy electrode or small-pixel test results (where feasible) or clear pathway to spectroscopic performance validation. Percentage of fabricated crystals (production yield) meeting target specifications, key process parameters identified for Phase II scale-up, and lessons learned. Analysis of potential product commercialization focusing on a commercial market at full scale production upon successful completion of the development. This should emphasis the technical and business need to reach full potential.

Scaling up output of crystal growth process. In Phase II, the laboratory process developed in Phase I shall be refined, optimized, and scaled to reliably produce multiple 44 × 44 × 15 mm (or equivalent) crystals with high reproducibility and yield. The goal is a manufacturing process achieving TRL 5, with consistent lot-to-lot performance that supports reliable detector fabrication and spectroscopic performance. At least one lot of crystals (minimum three to five crystals meeting all quality metrics, or equivalent total output across validated runs) shall undergo independent characterization and, where feasible, delivery to a qualified U.S. detector fabricator, end-user partner, or academic investigator (with DTRA approval) for pixelated electrode processing and performance evaluation in a representative radiation detection configuration. The final report shall document the optimized process, throughput, analytical quality control procedures, cost model, and percentage of output meeting all specifications. A clear pathway to Phase III commercial transition and DoW supply integration shall be provided. Phase II deliverables shall include: delivery of validated crystals to DTRA or a designated partner for independent evaluation; comprehensive process documentation suitable for technology transfer; and a detailed Phase III transition plan including potential commercial or DoW program insertion points.

Optional phase to continue scale-up, establish pilot production capability, and transition the domestic large-format CZT crystal growth process to commercial production. The objective is to achieve cost-competitive, on-shore supply of spectrometer-grade 44 × 44 × 15 mm (and larger) pixelated CZT crystals that can support multiple DoW programs and commercial radiation detection markets. This phase may include qualification of crystals in full-scale detector systems, establishment of quality management systems (e.g., ISO or equivalent), exploration of dual-use applications (medical imaging, industrial), and sustained production capacity demonstration.