The Nanoscale World
Forums » Forums » SPM Digest » Typical current noise value of Conductive AFM (Dimension 3100)?

Forums           

Bruker Media

Community Media

Bruker AFM Probes

SPM Digest

Application Notes

NanoTheater

Website

中文

Brochures & Datasheets

Publications

Probes Catalog

Events

Manuals & Documentation

Presentations

Guide to AFM Modes

News

Journal Club

Webinars & Video

Nanovations

Other

 

 

Typical current noise value of Conductive AFM (Dimension 3100)?

rated by 0 users
Not Answered This post has 0 verified answers | 2 Replies | 2 Followers

Top 25 Contributor
58 Posts
Points 652
stsolong posted on Wed, Jul 18 2012 9:38 AM

Hi friends,

1) The noise during the CAFM measurement suddenly changed. Before, the current noise was around 2pA (High current sensor 1nA/V). Now it is 10pA. Does it has something to do with the wear of the tip (SCM-PIC)?

2) By the way, I test the current signal on the sample chuck with a new tip. But the current signal appears until the DC sample bias reaches -4.2V or +4.8V. The bias is correctly controlled by the software because I verify this by a multimeter. So the question is why the conductive sample chuck has a threshold voltage? I expected the current image would increase as the bias increase. 

Thanks a lot!

  • | Post Points: 12

All Replies

Top 25 Contributor
55 Posts
Points 831
Bruker Employee
Reply
Chunzeng Li replied on Fri, Jul 27 2012 1:56 PM

Hi Solong,

1. How do you quantify the CAFM noise? It is peak-to-peak or RMS?

2. A couple of things to be aware of:

  • While the sample chuck is conductive on the macroscopic scale, it may not be so on the microscale/nanoscale, oxide may be present. The oxide can have different I-V characteristics than what you expect of an ideal conductor.
  • Make sure the tip coating is not damaged. Pt-Ir coating can be worn off during scan, or busted when high current flows thru the tip. In either case, the exposed Si tip is going to be a part in the current measurement.

Chunzeng

  • | Post Points: 17
Top 25 Contributor
58 Posts
Points 652
Reply
stsolong replied on Mon, Jul 30 2012 2:23 AM

Hello Chunzeng,

Thanks a lot for your reply!

 

1. I quantify the CAFM noise from peak to peak.

2. The Pt/Ir coating is only 20 nm thickness. On the bottom, the tip is also coated with 3nm Cr.  This coating is being used during the measurement. I almost cannot get the repeatable CAFM results of one sample. I don´t know when the Pt/ir coating has been totally worn off, when the Cr coating or Si takes a part in the current measurement.

  • | Post Points: 10
Page 1 of 1 (3 items) | RSS
Copyright (c) 2011 Bruker Instruments