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

9313650贝茨研究活动侧重于金属-半导体复合材料，用于检测电磁光谱中3-5微米波长部分的光辐射。用于该大气窗口热成像的两个重要探测器包括Hg1-x CDx Te(x=0.4-0.3)和Ptx Si肖特基势垒器件。(PTX-Si合金成分随烧结温度的不同而不同。)前者具有较低的本征载流子浓度(NO~1014 cm-3)和较高的电子迁移率(ue~105cm2/伏特-秒)等基本性能。以及与本征复合过程有关的约10-6秒的长少数载流子寿命。这些加在一起，使使用这种材料的系统获得了60%的巨大量子效率。量子效率是在吸收光子的基础上给出的。缺点包括两维阵列中的不均匀属性和较差的机械完整性。后一种材料虽然性质非常均匀，但热成像的量子效率低，约为1%，通常工作在80K以抑制暗电流。这些因素导致它们在3-5微米波长范围内没有得到更广泛的使用。这些研究中涉及的概念是使用掩埋肖特基势垒，这种势垒是通过在半导体矩阵中分散尺寸通常为5-50 nm的小金属颗粒来检测红外辐射而产生的。这些结构在选择平面结构中的金属厚度时避免了吸收和量子效率之间的权衡，这是导致其量子效率较低的原因之一。要研究的系统是p型硅基中的PtxSi颗粒，这一选择是基于以下几点：(A)像相同材料的平面结构一样，该系统可以对3-5微米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制造；(C)它们可以像平面结构一样，容易地并入使用基于硅的技术的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以及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.