If a material is supposed to be consisting of either intrinsic or extrinsic (or both) defects, how do they affect the physical characteristics of that material? Further, how one can differentiate their presence (whether it is intrinsic or extrinsic defect) in material?
This largely depends on the nature of the material and its defects. For example, For example, it can be microscopy (optical for transparent materials, atomic force), ultrasonic testing, destructive methods (microscopic examination not only of the surface but the cut of the materials, including optical, electron-microscopic, x-ray) and many others. The question is formulated too broadly. To be specified what type of materials and properties have in mind.
I am giving you few informative text material, powerpoint slides and a book by Professor Dr. Dieter Schroder. If you are working in device characterization, Professor Schroder's book is must keep for you. Hopefully from these attached documents you will find some idea. In my view intrinsic defects are well known and widely documented. Extrinsic defects vary over time and their determination and origin is not direct and easy. Most of the extrinsic defects are process generated due to rapid thermal processing and other high temperature stress or voltage stress conditions where interface and oxide traps can be generated. Extrinsic defects cause gate current or gate leakage current and are responsible for NBTI (negative bias temperature instability of threshold voltage, mobility, on current percentage change, transconductance), PBTI (positive bias temperature instability of these parameters), TDDB (time dependent dielectric breakdown), HCI (hot carrier injection) and RTN (random telegraph noise). Mostly these traps affect threshold voltage, drain current, transconductance and subthreshold slope of MOSFET devices. Extrinsic defects are also positioned relatively shallower in conduction band or valence band proximity whereas intrinsic defects including metal traps are positioned at mostly mid-band or mid gap level.
Sincerely,
Dr. Nabil Shovon Ashraf.
For insulators and semiconductors it is possible also to use the methods of thermally stimulated currents and impedance spectroscopy
Dear Alexander,
Thank you for your response. I also believe that my question was very general. It appears that it is biased towards Semiconductor Devices.
What I meant was basically related to optical spectroscopy. In a wide band gap material consisting defects (intrinsic or extrinsic), how one can relate these defects with physical characteristics obtained using optical means? I hope this explanation justifies my previous question.
Reg.,
Dear Nabil,
Thank you for your answer and references. My question was not meant for the devices. I'm sorry about that.
Reg.,
The book written by Professor Schroder and I attached, has a chapter on optical characterization method along with an exhaustive list of references. You should collect the articles from the references of book chapter as many as you can. Was it helpful to study the book? The PPT slides should be also helpful.
Sincerely,
Dr. Nabil Shovon Ashraf.
See if this PPT slide show is useful? It is based on luminescence of wide band gap different semiconductor defect characterization. Some band diagram and defect related transport and excitation are also shown in the slides which should explain the physical meaning of the defects interacting with free carriers and means of excitation.
Sincerely,
Dr. Nabil Shovon Ashraf.
Agrees with @Alexander. In purest material at 0 K, no defects but at higher temperature defects come in to picture even in purest material. So they are intrinsic defects. Assume material is not pure some impurities are there, further intrinsic defects are there. See NaCl and type of defects.
Add impurities intentionally by doping, more defects are produced. Few may be similar to intrinsic and few may be new type. Take NaCl:X. So it would be difficult to tell many times which are intrinsic and which are extrinsic. However, defects which are not common in pure and doped material may be surely due to doping and attempts may be made to distinguish them using techniques suggested by @Alexender. ESR is good technique sometimes.
Answer varies from material to material. Nature of F centre in NaCl will be of same in doped and pure-undeped NaCl.
Available in English - A.R. West's book "Basic Solid State Chemistry" (by the way, he is presents at RG). But in general - this is a separate science, with it's specifical methods. I'm not sure that all this methods can be listed in a short answer.
Regards.
Temperature dependent photoconductivity, impedance measurement as well as photoluminescence and cathodoluminescence can give information about defects .
Intrinsic defects are generated due to the presence of impurity in the materials, where as extrinsic defects are created due to some other effect such as effect of high energy ionizing irradiation effects. All the defects present in the sample will show its characteristic absorption in the visible range. Difference spectrum of the sample before and after irradiation can give different absorption peaks, which can be identified based on their nature. Even the photo luminescence also can provide important information about such defects.
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