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

9313650 Bates的研究活动集中在金属-半导体复合材料上，用于检测电磁波谱中3-5um波长部分的光辐射。在这个大气窗口中用于热成像的两个重要探测器包括Hg1-x Cdx Te （x=0.4至0.3）和Ptx Si肖特基势垒装置。（Ptx - Si合金成分随烧结温度的变化而变化。）前者具有较低的载流子浓度（无~1014 cm-3）和较高的电子迁移率（~ 105 cm- 2/伏特秒）等基本特性。由于固有的重组过程，少数载流子寿命约为10-6秒。这些结合在一起，使使用这种材料的系统具有高达60%的量子效率。量子效率是根据吸收光子给出的。缺点包括二维阵列的不均匀性和较差的机械完整性。后一种材料，虽然其性质非常均匀，但在热成像方面的量子效率很低，约为1%，通常在80k下工作以抑制暗电流。这些因素导致了它们在3-5um波长范围内缺乏更广泛的应用。这些研究涉及的概念是使用埋藏肖特基屏障，通过分散通常为5-50nm大小的小金属颗粒在半导体基质中产生，用于检测红外辐射。这些结构避免了在平面结构中选择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。所要研究的体系是p型硅基体中的PtxSi颗粒，选择该体系的依据是：(a)与相同材料的平面结构一样，该体系可以在3-5um波长范围内对辐射敏感；(b)这些结构可以由成熟的固态生长技术产生；(c)它们可以像平面结构一样，使用硅基技术作为一个更大系统的组成部分，并且；(d)量子效率、响应性和均匀性等特性可以很容易地与平面结构进行比较，以检验所涉及的理论和将其简化为实践的可行性。

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.