How to Use KikuchiLines X

Table of Contents

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Brief Introduction

KikuchiLines X is a simple program to simulate Kikuchi lines and RHEED (reflection high-energy electron diffraction) patterns. It is very simple so that it can not calculate line and spot intensities but only their positions.

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Outline of Operation

When you launch the application, the following window will appear.

New Window

To edit calculation conditions, press a lower right button . Then the following setting sheet will appear.

Settings Window

Details of the calculation parameters are shown in the "Details of Setting Parameters". After setting desired parameters, close the settings sheet and press Calculate button. After the calculation, the window will look like below.

Calculated Window

By default, blue lines are excess (bright in a real pattern) Kikuchi lines and yellow ones are defect (dark in a real pattern) lines. If you click on a line or a spot, it is highlighted by red color and its index will be shown in the index field.

In addition, you can overlay an experimentally obtained RHEED pattern. To add a RHEED pattern, click Choose Pattern button and select an image file. Most of the image formats such as TIFF/JPEG/GIF/PICT/PDF etc. (all of them can be treated by Preview application) are supported. This software does not have image processing functions, so that it is better to modify the pattern before using it. It is also recommended to set the image resolution to 72 dpi. If it has higher resolution, it will be degraded.

When you choose a RHEED pattern, it looks like this.

Pattern Window

Initially, RHEED pattern and calculated lines/spots does not fit. To move the pattern, drag it with option key. To change a size of the pattern, move the scale slider or enter a magnification number in the text field just right the scale slider. To change a rotation angle of the pattern, move angle slider or enter an angle (in degree) in the corresponding text field. After these adjustment, it should be like the following. Here, if the image resolution is 72 dpi and the camera length is set correctly, image size exactly matches the calculated one with magnification number of 1.

You can show/hide Kikuchi lines/RHEED spots/RHEED pattern by checking/unchecking corresponding check boxes below.

You can also save calculated lines/spots and RHEED pattern with calculation conditions. The RHEED pattern is included in the saved file (.kklx), thus you do not need to keep the original pattern.

Adjusted Window

Click on button opens a subwindow, in which calculation parameters are shown (Figure below). This text can not edit or save, however, you can select it and copy to anywhere else you want.

Drawer Window
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Details of Setting Parameters

Definitions

Before explaining setting parameters, you should know the following definitions. Axes are defined as the below figure. As shown in the figure, z axis is a surface normal direction, y axis is parallel to the surface and azimuthal index, x = y × z. The incident electron vector k0 comes from an azimuth direction which is rotated by φ (azimuthal rotation) and a glancing angle of θ.

Axes

The screen is placed at the opposite side of the incident electron beam as shown below. A camera length and a screen tilt angle are defined as shown in the figure.

Screen

The following figure shows a top view of the surface. A screen azimuthal angle ρ is defined as shown in the figure. Here, surface 2D structural unit vectors (a1 and b1) are also shown. For 1×1 unit, both a1 and b1 vectors are defined by corresponding x and y components in a0 unit, which is a lattice constant. For example, Si(111) case (a0 = 5.43Å), the surface unit is a diamond as shown in the figure and both of the unit vectors have length of a0/√2. In this case, a1 = (-1/2√2, √3/2√2) and b1 = (-1/2√2, -√3/2√2). For super structures such as 7×7, unit vectors are defined using a1 and b1. Therefore unit vectors for 7×7 are a2 = (7, 0) and b2 = (0, 7), those for √3×√3 are a2 = (1, -1) and b2 = (2, 1).

Unit

Parameters and Limitations

Crystal Structure

Crystal Structure Popup Menu
At present, simple cubic, FCC, BCC and diamond structure are supported.
Lattice Constant (a0)
Enter a lattice constant in Å unit.
Mean Inner Potential
Mean inner potential is a potential inside the crystal, which is related to refractive index. For silicon, it is known as 11~12 eV. If the crystal consists of a single element, this value may be few eV less than an atomic number of the element.

Surface Index

Surface Index
Vector components of surface normal direction. It can be fractional such as (1 1 1.5).
Azimuthal Index
Vector components of y parallel direction. It can also be fractional such as (1 1 -1.5). If this vector is not perpendicular to the surface index, surface parallel component of this vector is used.
Azimuthal Rotation
It defines incident electron direction k0. If is is zero, azimuthal direction is the same as azimuth index.

Calculation/Drawing Conditions

Electron Energy
Incident electron energy in keV unit.
Camera Length
Camera length in cm unit as defined above.
Screen Size
Screen width and hight in cm unit, i.e. calculation area size. The PC screen is assumed as 72 dpi.
Screen Tilt and Azimuth
Screen tilt and azimuthal angle defined above.
Index Range
Kikuchi line index range. If it is 5, (-5 -5 -5) to (5 5 5) indices are calculated.
h+k+l
This sets maximum index sum of h, k and l. If this is 10 and the index range is 5, (5 5 0) is calculated but (5 5 1) is ignored.
Resolution
Line calculation resolution. If it is a small value, precision increases but calculation time also increases. For normal use, 100~200 is proper value.
Line Colors
It defines colors for excess lines (bright lines in a real pattern), defect lines (dark lines in a real pattern) and selected line/spot. You can choose colors by clicking on a color rectangle. Opacity also works.
Suppress Defect Lines
If checked, only excess lines are calculated.

RHEED Pattern Calculation

Incident Glancing Angle
Glancing angle of the incident electron in degree.
1×1 Unit
If the checkbox is checked, 1×1 RHEED pattern will be calculated.
A text field at the right side of the check box is a comment to the structure. Use it freely.
The unit vectors a1 and b1 are defined above. Be sure that the unit length is the lattice constant a0.
Color and size defines drawing spot color and size (radius). For the color, opacity also works.
n-th Reconstruction (n = 2~4)
If the checkbox is checked, RHEED pattern for super structure defined here will be calculated.
A text field at the right side of the check box is a comment to the structure. Use it freely.
The unit vectors an and bn are defined above. Be sure that those vectors are defined using a1 and b1.
Colors and sizes are the same meaning as 1×1 unit.
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