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利用吉时利6517A型静电计，可以在高达1000V的高压下实现低噪声（未滤波1fA_p-p）电流测量。利用精心设计的测量室和质量优良的绝缘体，可以完全避免漏电流，精确测量高达10¹⁷W的电阻。如果温度稳定性优于0.1K，那么在温度依存性测量或光电导率测量期间，可以维持这个测量能力。利用SF₆气体或高真空可以抑制高压电极之间空气的电子击穿。如果分子束沉积高真空系统中的线缆和泵浦得到屏蔽，可以在薄膜生长过程中对电流进行现场测量，而且具有相同的灵敏度，这对像有机分子材料这样的低电导率材料特别有用。

Current measurements at low noise levels (1fAp-p without filtering) can be performed at a maximum of 1000V with a Keithley 6517A Electrometer. By using a carefully designed measurement chamber and good quality insulators, leakage currents can be completely avoided, which allows measuring resistances up to 1017W accurately. This measurement capability can be maintained during temperature dependent or photoconductivity measurements if the temperature stability is better than 0.1K. Electrical breakdown of air between the electrodes at high voltages can be suppressed using an SF6 atmosphere or high vacuum. If cables and pumps inside a Molecular Beam Deposition high vacuum system are shielded, current measurements can be done in-situ during thin film growth with the same sensitivity, which is especially useful for materials with low conductivity like organic molecules.

致谢

吉时利仪器公司感谢新西兰麦克德尔米德先进材料和纳米技术研究所（惠灵顿市）的Felix Budde博士对本应用笔记的帮助。为了研究电荷载体的生产和再结合，Budde博士曾在德国斯图加特大学学习物理，并对有机薄膜的光电导率进行测量。作为其在瑞士伯尔尼大学博士工作的一部分，他准备了有机晶体，并利用光学和电子测量手段对其进行分析。Budde博士的联系方式是： SCPS,P.O. Box 600, Wellington, New Zealand (email:Felix.Budde@vuw.ac.nz)。

Keithley Instruments would like to thank Dr. Felix Budde of theMacDiarmid Institute of Advanced Materials and Nanotech-nology in Wellington (New Zealand) for contributing this appli-cation note. Dr. Budde studied Physics at the University ofStuttgart (Germany) and measured photoconductivity of organicfilms to study generation and recombination of charge carriers.As part of his PhD work at the University of Berne (Switzer-land), he prepared organic crystals and analyzed them with opti-cal and electrical measurements. He can be contacted at SCPS,P.O. Box 600, Wellington, New Zealand (email:Felix.Budde@vuw.ac.nz).