EEPW论坛

在比某种材料波长较短的波长范围里，光能足以激发电子从电极材料发射。这将导致电极之间气体的离子化，提供导电路径。如果在高真空中进行测量，这些电子将产生额外电流。为了避免这些效应，选择的照明波长应当大于光电效应阈值波长。对于镓来说，这个波长是295nm。

At wavelengths shorter than a certain material-dependent wave-length, light is energetic enough to induce emission of electronsfrom the electrode material. This leads to an ionization of the gasbetween the electrodes, providing a conductive path. If the mea-surement is performed in high vacuum, these electrons producean additional current. To avoid these effects, the wavelengthchosen for illumination should be greater than the threshold forthe photoelectric effect. For gallium, this wavelength is 295nm.

Stored Charges累积电荷

假设电荷存储于许多绝缘体(尤其是特氟纶)，那么在改变施加电压或温度后，可能需要几个小时的时间才能达到电荷平衡，尤其是对于具有极高阻抗的样本而且施加电压较高的时候更是如此。因此，要等到电流达到平衡后，再进行测量。

Given that charges are stored in many insulators (especiallyTeflon), it may take hours for the current to reach equilibriumafter changing the applied voltage or temperature, especially forsamples with very high resistances and at high applied voltages.Don’t start the measurement until equilibrium is reached.

设备清单

• 6517A型静电计

• 低噪声三芯同轴转接电缆

• PC、IEEE线缆等

• SF₆气瓶

• 镓

• 定制的测量室，包括三芯同轴转接电缆以及高压馈通