Impact of the contact metallization on the performance of photoconductive THz antennas.
Impact of the contact metallization on the performance of photoconductive THz antennas.
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DOI：
10.1364/oe.16.019695
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发表时间：
2008-11
期刊：
影响因子：
3.8
通讯作者：
N. Vieweg;Martin Mikulics;M. Scheller;K. Ezdi;Rafal Wilk;H. Hübers;Martin Koch
中科院分区：
文献类型：
--
作者：
N. Vieweg;Martin Mikulics;M. Scheller;K. Ezdi;Rafal Wilk;H. Hübers;Martin Koch
AuGe基合金和Ti/Au金属层堆叠都广泛用作由低温生长的GaAs制成的光电导太赫兹天线的欧姆金属接触。在这里，我们首次对这两种金属化类型进行系统比较。这两种类型的一系列天线均由飞秒激光脉冲和两个二极管激光器的发射激发，即我们测试作为脉冲太赫兹发射器和光电混合器的结构。在这两种情况下，都采用相干和非相干检测方案。我们发现具有 AuGe 金属化层的天线发射的功率比具有 Ti/Au 金属层的天线高 50%。通过与光混频器模型的比较，我们得出结论，较高的输出功率是由 AuGe 触点的较低接触电阻导致的，从而导致电流增加。然而，钛/金触点具有更高的热稳定性，如果需要高系统稳定性，这可能是有利的。
Both AuGe based alloys and Ti/Au metal layer stacks are widely used as ohmic metal contacts for photoconductive THz antennas made of low temperature grown GaAs. Here, we present the first systematic comparison between these two metallization types. A series of antennas of both kinds is excited by femtosecond laser pulses and by the emission from two diode lasers, i.e. we test the structures as pulsed THz emitters and as photomixers. In both cases, coherent and incoherent detection schemes are employed. We find that the power emitted from the antennas with AuGe metallization is 50% higher than that of antennas with a Ti/Au metal layer. From a comparison with a photomixer model we conclude that the higher output power results from a lower contact resistance of the AuGe contacts leading to an increased current flow. However, Ti/Au contacts have a higher thermal stability which might be advantageous if high system stability is called for.