Asylum Research

 

AR-PPLN Test Sample

For Piezoresponse Force Microscopy

The AR-PPLN Test Sample is a convenient and reliable sample for practice, setup, and verification for a wide variety of Piezoresponse Force Microscopy (PFM) techniques. This includes, but is not limited to, imaging and point hysteresis loops. The reference sample has stripe domains permanently polarized for easy identification and optimization of PFM parameters.

Description
The Periodically Poled Lithium Niobate Test Sample (AR-PPLN) consists of a 3mm x 3mm LiNbO3 transparent die that is 0.5mm thick. The active area is an alternating pattern of oppositely poled stripe domains that are parallel to one axis of the die and cover the entire die surface. The pitch of the domains is 10µm.

The AR-PPLN Test Sample is produced on a lithium niobate wafer. The process starts with poling the wafer with a very strong electric field to create a homogeneously poled substrate with a polarization axis orthogonal to the wafer surface. A single lithographic photomask is used to print a mask of parallel stripes on one side of the wafer. It is then polarized in the opposite direction, which affects only the unmasked striped areas and propagates through the entire thickness of the wafer. Because of the close spacing of the unmasked regions, the polarization can “wander” laterally through the wafer thereby making the 10µm pitch periodic polarization best on one side of the wafer and somewhat random on the other side.

For PFM investigation of the AR-PPLN Test Sample, the sample should be electrically connected to a sample holder in an AFM setup (Figure 1). The Test Sample should be stable for PFM applications at applied potentials less than 50V because of its high coercive field. The Phase and Amplitude data channels show the piezoelectric effect (Figure 2). For typical PFM hysteresis loops, the switching voltage frequently exceeds 100V (Figure 3). To attain these large voltages, the use of an integrated high voltage amplifier, such as Asylum’s HVA220 Amplifier, is necessary.

Handling
Use care when handling or using the PPLN calibration standard; it is sensitive and can easily be damaged or broken. Some suggestions for its care:

  1. Handle the outer edges or the mounting only. Never touch the active area.
  2. Handle in a clean environment and use gloves when possible.
  3. Always return to its package when not in use and store in a safe place.
  4. Use dry filtered nitrogen to blow off any debris. Otherwise, do not attempt to clean.

PPLN Configurations
The AR-PPLN comes in three configurations:

  1. Model: 900.241 – Mounted on a 15mm diameter steel puck
  2. Model: 900.242 – Mounted on a 3" x 1" microscope slide
  3. Model: 900.243 – Unmounted

Specifications subject to change.

 

 

Download AR-PPLN Test Sample PDF

 

Figure 1: The AR-PPLN (unmounted) clipped into a High Voltage sample holder. Note that the sample is mounted at ~45° relative to the axes of the scanner, insuring domain contrast if the cantilever is scanned at either 0° or 90°.

 

Figure 2: Vertical PFM phase (a) and amplitude (b) overlaid on the rendered topography for the AR-PPLN Test Sample. Lateral phase (c) and amplitude (d) were imaged simultaneously. Imaging performed with an Olympus Electri-lever. 50μm scan.

 

Figure 3: PFM-DART (Dual AC Resonance Tracking) image of reversal domains created by applying negative 120V in a 6x6 square array, 6μm scan.

 


Oxford Instruments Asylum Research, Inc. • 6310 Hollister Ave. • Santa Barbara, CA  93117 • +1-805-696-6466AFM.info@oxinst.com