Pra.Ma.

STEPP is a Silicon Test Echeloned Pattern for AFM height calibrating in angstrom and single nanometer intervals by the naturally calibrated monoatomic silicon step with the height 0,31nm.

STEPP

About STEPP calibration sample

The Silicon Test Echeloned Pattern STEPP for AFM is designed on the base of silicon (111) surface with verified distribution of monoatomic steps as main calibrating inits for the complex control of AFM set up:

• Height calibrating in angstrom and single nanometer intervals on the monoatomic steps;
• Using the as the substrate for investigations of bio-objects, particulate matter and other;
• More precision diagnostic of nanoobjects.

 Specification:

• Chip size - 1x4x0.3 mm³
• Average interstep distance  ~  0,5-2 µm
• Misorientation of surface from the (111) plate ~ 1°
• Single monoatomic step height 0,314 nm
• Average roughness of the area without monoatomic steps (terrase)  - 0,06 nm

Instruction manual:

To calibrate AFM on the Z axis the following additional operations are to be performed:

• Place the STEPP on the flat horizontal working area under the AFM probe.
• Approach to the STEPP surface and make topography scanning in the height measure mode using the scan size 20µm or larger. After obtaining topographic AFM image with step bunches (Fig.1) choose the place ~5x5 µm between bunches and try to obtain AFM-image with regular monoatomic steps only.
• After obtaining good topography AFM-image of the STEPP surface with the system of monoatomic steps use the software filter "Plane Substraction" on the wider single  terrace. (Fig.2)

• Choose the area on the AFM-image for obtaining height spectra by using possibilities of AFM software. Please, choose the region for  measurements which is closer  to the terrace which was used for image equation.
• After obtaining height spectra with peaks which are corresponded to each terrace, measure the interpeak distance. Change the calibrating constant while interpeak distance becomes 0,31 nm. Please, remember that the experimental error of your measurement is the half width of the peaks on their half height, try to obtain narrowest peaks! (Fig.3)