HOT-ELECTRON EFFECTS IN METALS
HOT-ELECTRON EFFECTS IN METALS
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DOI：
10.1103/physrevb.49.5942
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发表时间：
1994-03-01
影响因子：
3.7
通讯作者：
CLARKE, J
中科院分区：
文献类型：
--
作者：
WELLSTOOD, FC;URBINA, C;CLARKE, J
当足够的电功率P在金属薄膜中以毫伏的温度耗散时，电子可以被驱动到远离声子的热平衡。对于体积欧米伽中的均匀功率耗散，我们证明了电子达到稳态温度T(E)=(P/SIGMAOEMGA+T(P)5)1/5，其中T(P)是声子温度，Sigma是涉及电声子耦合的参数。我们用基于直流超导量子干涉器件(SQUID)的灵敏安培计测量了AuCu薄膜中奈奎斯特电流噪声随P的变化，从而推导出T(E)。我们用单参数Sigma对我们的数据进行了理论拟合，发现Sigma=(2.4+/-0.6)×10(9)Wm-3K-5符合得很好。当我们通过连接薄膜散热片来增加电阻的体积时，对于给定的功率损耗，电阻中T(E)的增加要小得多，这与一个简单的非均匀加热模型定性地一致。我们还测量了低温下直流SQUID中的磁通噪声，发现白噪声受到约瑟夫森结电阻分流中电子加热的限制。通过在分流管上安装冷却翅片，我们能够大大减少这些影响。
When sufficient electrical power P is dissipated in a thin metal film at millikelvin temperatures, the electrons can be driven far out of thermal equilibrium with the phonons. For uniform power dissipation in a volume OMEGA we show that the electrons attain a steady-state temperature T(e) = (P/SIGMAOEMGA + T(p)5)1/5, where T(p) is the phonon temperature and SIGMA is a parameter involving the electron-phonon coupling. We have used a sensitive ammeter based on a dc superconducting quantum interference device (SQUID) to measure the Nyquist current noise in thin films of AuCu as a function of P, and thus inferred T(e). We fitted our data to the theory with the single parameter SIGMA, and found good agreement for SIGMA = (2.4+/-0.6) X 10(9) Wm-3 K-5. When we increased the volume of the resistor by attaching a thin-film cooling fin, there was a much smaller increase in T(e) for a given power dissipation in the resistor, in qualitative agreement with a simple model for nonuniform heating. We also measured the flux noise in dc SQUIDs at low temperatures, and found that the white noise was limited by heating of the electrons in the resistive shunts of the Josephson junctions. We were able to reduce these effects substantially by attaching cooling fins to the shunts.