OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Directed Energy (DE) The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: The overall goal of the R&D effort is to develop high optical quality compositionally uniform wafers of the ternary semiconductor alloy InAsP with different alloy compositions. The wafer sizes should be approximately 20 to 25 mm in cross section dimensions, and above 1 mm in thickness. DESCRIPTION: Sensitive infrared detectors, especially for the short wave infrared spectral range are fabricated by growing semiconductor alloy thin films having different compositions on high quality substrates. The substrate needs to be of high electronic quality, i.e., it must be of high compositional uniformity, possess very few defects, and ideally be lattice matched with the thin films being grown. Moreover, for application as windows, the optical quality of the substrate needs to be high, i.e., they must transmit light at the desired wavelength range with as little absorption or scattering as possible. Ternary alloy semiconductors, due to their flexible optical transmission ranges, are ideal for sensor application. However, there are no commercial suppliers for bulk ternary alloy InAsP and it is very important for the Air Force to have a domestic supply source for such a material. PHASE I: In small scale internal effort, InAsP crystals have been gorwn in bulk form and has proven ready to move directly into a Phase II. Therefore, a Phase I award is not required. The offeror is required to provide detail and documentation in the Direct to Phase II proposal which demonstrates accomplishment of a Phase I-like effort, including a feasibility study. This includes determining, insofar as possible, the scientific and technical merit and feasibility of ideas appearing to have commercial potential. It must have validated the product-market fit between the proposed solution and a potential AF stakeholder. The offeror should have defined a clear, immediately actionable plan with the proposed solution and the AF customer. The feasibility study should have; -Identified the prime potential AF end user(s) for the non-Defense commercial offering to solve the AF need, i.e., how it has been modified; -Described integration cost and feasibility with current mission-specific products; -Described if/how the demonstration can be used by other DoD or Governmental customers. PHASE II: The government envisions a design of experiments (DOE) type of approach to optimize yield of optically clear, bulk, semiconductor materials for use as refractive elements in electro-optical infrared systems operating in the shortwave infrared (SWIR) band. These systems typically operate at wavelengths between 1 and 1.7 m. It is anticipated that a material with flexible transmission range in this band will be integrated with independent sensor development and improvement work to provide the desired capabilities to the DoD. Proposals should discuss a path towards developing compositionally uniform crystals with high optical quality, with clear apertures of 20 mm diameter, and in thicknesses of more than 1 mm. Ways to increase the yield of high-quality crystals should also be addressed in the proposal. Wafer-like parts should have consistent spectral performance, such as transmission and bandgap/cut-on wavelength across the clear aperture and throughout the bulk. As-grown material should exhibit minimal linear absorption and scattering losses due to crystal defects or impurities or inhomogeneities. The cut-on wavelength is defined here as the wavelength at which the linear transmission of the sample is 0.01, i.e., 1%, and at wavelengths longer than which the sample transmission increases to the 50% or higher, and ideally to the transmission limit imposed by surface reflections. The desired cut-on wavelength of the material is between 1.5 and 1.6 micrometers. The grown wafers should be mechanically robust to allow cutting, shaping and polishing to meet typical optical quality surface specifications such as flatness, parallelism and scratch-dig. There is also interest in metrology development for evaluating the bulk semiconductor material either during growth or immediately post growth, but prior to initial cutting or rough polish. For example, ensuring that the grown material has the desired optical bandgap prior to additional processing steps is of interest. Similarly, evaluation of material properties, such as dopant concentration, carrier lifetimes, mobility's, etc., as functions of the DOE process is also of relevance. The impact of post growth treatment, such as high temperature annealing, could also be a component of the DOE. Tasking Requirements: The proposer will demonstrate that A ternary alloy can be grown with cut-on wavelength between 1.5 and 1.6 m and linear cross section dimensions not less than 5 mm over the sample face the cut-on wavelength should not vary more than 0.5% as measured over the sample area. the transmission of the material should increase at wavelengths longer than the cut-on wavelength and reach within 10% of the predicted value with only surface reflection loss scattering losses of the grown and polished wafers due to surface roughness, crystal defects or impurities or inhomogeneities over the desired SWIR wavelength range will be minimal, as determined qualitatively by high resolution infrared imaging and subsequently quantitatively by the modulation transfer-function (MTF)' measurement in an infrared optical system. With the insertion of the two-side-polished material, the spatial frequency at which the MTF value of the infrared system drops by 50% should not be less than 30 line-pairs/mm After the requirements listed above are met for wafers with linear cross-section dimensions of ~ 5 10 mm, wafers with identical or better quality and dimensions exceeding 15 mm will be grown. Wafer-like parts should have consistent spectral performance, such as transmission and bandgap/cut-on wavelength across the clear aperture and throughout the bulk. As-grown material should exhibit minimal linear absorption and scattering losses due to crystal defects or impurities or inhomogeneities. The cut-on wavelength is defined here as the wavelength at which the linear transmission of the sample is 0.01, i.e., 1%, and at wavelengths longer than which the sample transmission increases to the 50% or higher, and ideally to the transmission limit imposed by surface reflections. The desired cut-on wavelength of the material is between 1.5 and 1.6 um. The grown wafers should be mechanically robust to allow cutting, shaping and polishing to meet typical optical quality surface specifications such as flatness, parallelism and scratch-dig. There is also interest in metrology development for evaluating the bulk semiconductor material either during growth or immediately post growth, but prior to initial cutting or rough polish. For example, ensuring that the grown material has the desired optical bandgap prior to additional processing steps is of interest. Similarly, evaluation of material properties, such as dopant concentration, carrier lifetimes, mobility's, etc., as functions of the DOE process is also of relevance. The impact of post growth treatment, such as high temperature annealing, could also be a component of the DOE. Tasking Requirements: The proposer will demonstrate that 1. A ternary alloy can be grown with cut-on wavelength between 1.5 and 1.6 um and linear cross section dimensions not less than 5 mm over the sample face 2. the cut-on wavelength should not vary more than 0.5% as measured over the sample area. 3. the transmission of the material should increase at wavelengths longer than the cut-on wavelength and reach within 10% of the predicted value with only surface reflection loss 4. scattering losses of the grown and polished wafers due to surface roughness, crystal defects or impurities or inhomogeneities over the desired SWIR wavelength range will be minimal, as determined qualitatively by high resolution infrared imaging and subsequently quantitatively by the modulation transfer-function (MTF)' measurement in an infrared optical system. With the insertion of the two-side-polished material, the spatial frequency at which the MTF value of the infrared system drops by 50% should not be less than 30 line-pairs/mm 5. After the requirements listed above are met for wafers with linear cross-section dimensions of ~ 5 10 mm, wafers with identical or better quality and dimensions exceeding 15 mm will be grown. Contract deliverables: Wafers with consistent spectral performance as identified above will be delivered for evaluation. Monthly reports detailing work-progress will be delivered. Final report describing the crystal growth technique, necessary improvements and results obtained will be delivered at the end of the program. PHASE III DUAL USE APPLICATIONS: The contractor will pursue commercialization of the various technologies developed in Phase II for transitioning expanded mission capability to a broad range of potential government and civilian users and alternate mission applications. Direct access with end users and government customers will be provided with opportunities to receive Phase III awards for providing the government additional research & development, or direct procurement of products and services developed in coordination with the program. REFERENCES: 1. R. E. Nahory, M. A. Pollack, W. D. Johnston, and R. L. Barns, Band gap versus composition and demonstration of Vegard's law for In1-xGaxAsyP1-y lattice matched to InP , Appl. Phys. Lett. 33, p659-661, (1978). 2. M. W. Wanlass, S. P. Ahrenkiel, R. K. Ahrenkiel, J. J. Carapella, R. J. Wehrer, and B. Wernsman, Recent advances in low-bandgap, InP based GaInAs/InAsP materials and devices for thermophotovoltaic (TPV) energy conversion , AIP Conf. Proc. 738, p427-435, (2004). KEYWORDS: Semiconductors; Bulk Crystals; Wafers; Ternary Alloys; Short Wave Infrared (SWIR) detectors;
