TER_sl: X-ray specular reflection from multilayers with rough interfaces
Introduction Program Guide Conditions of use Access to TER_sl Retrieve results Automation/fitting

Introduction

This page is a CGI interface to my program TER_sl simulating x-ray specular reflection from multilayers with the account for interface roughness or transition layers. The method implemented in TER_sl is the recursive matrix algorithm (RMA) developed for grazing-incidence x-ray diffraction. The RMA is neither Parratt's nor Abeles', although it can be reduced to each of them. The advantage of RMA is that the same code works for both the diffraction and reflection problems.

 Starting July 2005 the program can also calculate and print the intensity of standing waves inside the target. The standing waves can be used to analyze secondary photo emission effects like fluorescence, the formation of periodic wavefields inside multilayers, the Yoneda effect, and etc.



Program Guide

This short guide provides some explanations on the TER_sl data input and outlines the restrictions of this Web interface.

The TER_sl program is executed on my PC, which runs a Web server under Windows operating system. Since this PC is shared by all of the WEB users of my x-ray library, please, avoid overloading the server by running multiple tasks at the same time.

To obtain the results from TER_sl you need to fill out the input form and click on the SUBMIT button. If your input is correct, the results will be presented as a figure and a reference to downloadable ZIP file with the data. Otherwise, an error report will be returned.

The specification of surface layer profile is implemented with a simple script language. A typical syntax is:

; comments are allowed in any line, but should not contain special symbols like '"*?$!@%
period=5
t=10 code=GaAs w0=0.8 sigma=2
t=10 code=GaAs x=0.3 code2=AlAs x2=0.7 sigma=2
t=10 code=SiGe rho=0.9 sigma=2
t=10 x0=(5e-4,7e-6) tr=5
t=10 w0=.5 tr=4
t=10 w0=0.5
t=10
end period

Here:

Here is a practical example -- a profile for 20-period AlAs/GaAs superlattice with 100 Angstroms of GaAs and 70 Angstroms of AlAs in each period; the structure is covered by additional 200A of GaAs and, finally, there is some 20A amorphous oxide layer on the surface:

; Oxide layer:
t=20. w0=0.7
; -- w0=0.7 because of reduced layer density

; Cap layer:
t=200.
; -- when the code is not specified, the substrate code (GaAs) is used

; Superlattice:
period=20
  t=100.
  t=70. code=AlAs
end period

For the rest of parameters you are suggested to follow the common sense. To ensure that your input was correct, please verify respective listing file -- a file with the ".TBL" extension in the ZIPped archive referred from the TER_sl results screen.



Access to TER_sl

To simplify understanding the TER_sl you are provided the templates listed below. All the templates link to the same program and provide the same functionality. They differ by preloaded data to demonstrate some possible applications of TER_sl.
Besides, when submitting the TER_sl task, it is possible to check the progress watching option. The progress watching is obviously more comfortable, but it might not work with some old Web browsers. Also, it is a bit slower because of putting an additional load on the network and launching each 5 seconds a watch program on my computer. Welcome to try both of the ways and choose the most convenient for your needs.

 New of April-2012: POST-Method Templates

1. Specular reflection from perfect reflectors
Use this to check the width and shape of total reflection curves and to analyze x-ray mirrors.
 
2. Specular reflection from multilayers
Use this e.g. for A3B5, A2B6, SiGe and other semiconductor structures, W/C multilayer mirrors, etc.
 

1a. Specular reflection from perfect reflectors + standing waves
Use this to check the width and shape of total reflection curves and to analyze x-ray mirrors.
 
2a. Specular reflection from multilayers + standing waves
Use this e.g. for A3B5, A2B6, SiGe and other semiconductor structures, W/C multilayer mirrors, etc.

GET-Method Templates
This is an older, but better tested method. Generally it works very well except for
known problems with IE browser & some firewalls for structure description exceeding 2K bytes.

1. Specular reflection from perfect reflectors
Use this to check the width and shape of total reflection curves and to analyze x-ray mirrors.
 
2. Specular reflection from multilayers
Use this e.g. for A3B5, A2B6, SiGe and other semiconductor structures, W/C multilayer mirrors, etc.
 

1a. Specular reflection from perfect reflectors + standing waves
Use this to check the width and shape of total reflection curves and to analyze x-ray mirrors.
 
2a. Specular reflection from multilayers + standing waves
Use this e.g. for A3B5, A2B6, SiGe and other semiconductor structures, W/C multilayer mirrors, etc.



Retrieve results

Here is a tool to retrieve the results of finished jobs if you know the job ID. Some possible uses of this tool are:

  1. You started a job with the progress watch option; the server returned the job ID and began reporting the progress. However, you found that the calculations would take too long. Then, you may break the connection and retrieve the data later on with this tool. If the calculations are not finished, the tool will resume the watch process.
  2. The data are accidentally deleted from your client computer and you want another copy of them. In this case you should be aware that results are usually stored on the server for about one day after respective job is finished.
Job ID:



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