Nanostructured Pt-x-Si-P-Type Composite Studies for 3-5um Radiation Detection

9313650贝茨研究活动的重点是金属半导体复合材料的光辐射在电磁波谱的3- 5 um波长部分的检测。 两个重要的探测器用于热成像在这个大气窗口包括Hg 1-xCdxTe（x=0.4至0.3）和PtxSi肖特基势垒器件。 (The Ptx Si合金成分随烧结温度而变化。 前者材料具有吸引人的基本性质，如低的本征载流子浓度与no~1014 cm-3，高的电子迁移率UE~ 105 cm 2/伏秒。以及与本征复合过程相关的大约10-6秒的长少数载流子寿命。 这些联合收割机使使用这种材料的系统具有60%的大量子效率。 量子效率是根据吸收的光子给出的。 缺点包括二维阵列中的不均匀性质和差的机械完整性。 后者的材料，虽然在其性质非常均匀，遭受约1%的热成像的低量子效率，通常在80 K下工作，以抑制暗电流。 这些因素导致它们在3- 5 um波长范围内没有更广泛的使用。 在这些研究中涉及的概念是使用掩埋肖特基势垒，如通过在半导体基质中分散通常5- 50 nm大小的小金属颗粒来产生，用于检测红外辐射。 这些结构避免了在选择平面结构中的金属厚度时吸收和量子效率之间的权衡，这导致了它们的低量子效率。 待研究的系统是p型硅基质中的PtxSi颗粒，并且该选择基于以下： (a)与相同材料的平面结构一样，该系统可以对3- 5 μ m波长范围内的辐射敏感;（B）这些结构可以通过成熟的固态生长技术来生产;（c）与平面结构一样，它们可以容易地结合为使用硅基技术的较大系统的整体部分;（d）可以容易地将诸如量子效率、响应度和均匀性之类的特性与平面结构进行比较，作为对所涉及的理论和将其转化为实践的可行性的测试。

9313650 Bates Research activities focus upon metal-semiconductor composites for the detection of optical radiation in the 3-5um wavelength portion of the electromagnetic spectrum. Two important detectors used for thermal imaging in this atmospheric window include Hg1-x Cdx Te (x=0.4 to 0.3) and Ptx Si Schottky barrier devices. (The Ptx Si alloy composition varies with the sintering temperature.) The former material has attractive fundamental properties such as a low intrinsic carrier concentration with no~1014 cm-3, a high electron mobility of ue~ 105 cm 2/volt-sec. and long minority carrier lifetimes on the order of 10-6 seconds associated with intrinsic recombination processes. These combine to give systems using this material large quantum efficiencies of 60%. Quantum efficiencies are given on the basis of absorbed photons. Disadvantages include nonuniform properties in two-dimensional arrays and poor mechanical integrity. The latter material, though very uniform in its properties, suffers from low quantum efficiencies of about 1% for thermal imaging and are normally operated at 80 K to suppress the dark current. These factors have contributed to the lack of their more widespread use in the 3-5um wavelength range. The concept involved in these studies is the use of buried Schottky barriers, as produced by dispersing small metal particles typically 5-50nm in size, in semiconducting matrices for the detection of infrared radiation. These structures avoid the trade-off between absorption and quantum efficiency in the choice of metal thickness in the planar structures which contributes to their low quantum efficiencies. The system to be investigated is PtxSi particles in a p-type silicon matrix and this choice is based on the following: (a) like the planar structures of the same materials this system can be made sensitive to radiation in the 3-5um wavelength range; (b) these structures may be produced by well established solid- state growth techniques; ( c) they may be, like the planar strucutures, readily incorporated as an integral part of a larger system using silicon-based technology and; (d) properties such as quantum efficiency responsivity and uniformity may be readily compared to the planar structure as a test of the theory involoved and the feasibility of reducing it to practice.