Questions on Rs measurement by four point probe device

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SUMMARY

The discussion centers on measuring the sheet resistance (Rs) of CuO thin films using the Agilent B1500 device. The user reports significant variability in Rs measurements after a two-step annealing process, where the first step shows metallic behavior but the second step leads to inconsistent Rs values ranging from a few ohms/sq to Gohms/sq. The user also notes potential issues with probe contact and chemical reactions affecting measurements. This highlights the challenges in accurately measuring Rs for CuO thin films in electronic applications.

PREREQUISITES
  • Understanding of sheet resistance measurement techniques
  • Familiarity with thin film deposition methods, specifically RF sputtering
  • Knowledge of the Agilent B1500 device and its measurement capabilities
  • Basic principles of semiconductor physics and material properties of CuO
NEXT STEPS
  • Research best practices for measuring sheet resistance using four-point probe techniques
  • Investigate the effects of annealing processes on CuO thin films
  • Learn about alternative probe materials and geometries to minimize measurement errors
  • Explore scientific literature on the electrical properties of CuO and its applications in TFTs
USEFUL FOR

Researchers and engineers working with thin film materials, particularly those focused on electronic applications involving CuO, as well as anyone involved in optimizing measurement techniques for sheet resistance in semiconductor devices.

Hanyuri
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Hi all,
I am working on electronics material (using metal oxide as an active layer in TFTs). Currently, I'm trying to measure the sheet resistance (Rs) of CuO thin film (~100nm in thickness). My lab uses Agilent B1500 device for measuring the Rs. I met some problems when carrying out the measurement:

For my case, CuO nanoparticle solution is deposited and is annealed by 2 step annealing ( in inert gas first and then is oxidized in very low % O2). At the first step, the samples has very low and specific Rs, which showed as a metallic material (Cu), but after the second step, the Rs is not clearly. The Rs drop at every different current points are varied widely and not specific from a few ohms/sq. (I~1-100mA) to Gohms/sq. (I~1-100nA). If they are insulating, there should be no voltage drops between the probes. I wonder why it happened like that and whether there is any wrong in my measurement.

I alse referred some other scientific articles. They reported that CuO thin film has Rs ~ tens of kohm/sq (the deposition method is RF sputtering).

This measurement is very important for my research. I hope that some of you have done this measurement before.
I will greatly appreciate if somebody can help me for this case. Please feel free to contact me if you nees any further information.
 
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CuO is mechanically very weak . It is very easy to punch right through it or at least reduce local thickness with probes .

Pointed probes are particularly problematic . Small diameter spherical end probes give a variable contact area and indentation depending on applied load .

Copper oxide can react with some probe metals to produce a small voltage .
 

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