# Seminar: Semiconductors
Topics for Winter Term 07/08

General Topics | Team | Assistant | Date
Recommended Topics will be marked in Red
1. Introduction
| Semiconductor Products and Materials |  |  |
| Give a general review |  |  |
| Cover present products and their dependence on certain semiconducting properties Find some useful order criteria - either by material properties or by applications |  |  |
| Cover emerging products and technologies Give a list of desirable properties that have not yet been obtained - the present research issues! |  |  |
2. Basic Semiconductor Physics
| Limits and Scaling |  |  |
| Generate or improve upon the basic content of chapter 3.3 |  |  |
| Discuss limits, e.g. leakage currents, degeneration for doping, maximum life time, tunneling in the semiconductor and through layers, avalanche break-through, ...; whereever possible with some theory. |  |  |
| Describe what happens if everything is scaled down, which kinds of limits from above are critical for scaling, and new limits that may appear at small dimensions. |  |  |
| Experimental Methods for Measuring Band Structures |  |  |
| List and discuss major methods. |  |  |
| Compare relative merits and shortcomings. |  |  |
| Give some special results. |  |  |
| Calculations of Band Structures |  |  |
| Give a general review of the different methods. |  |  |
| Compare relative merits and shortcomings. |  |  |
| Give some special results. |  |  |
3. Silicon: General Properties and Technologies
| Thin Film Si Solar Cells |  |  |
| Amorphous Si, but essentially "thin" crystal. Si. |  |
| Discuss developments, pro and cons, new ideas. |  |
| Technical Diodes |  |  |
| Describe the specialities of important technical diodes (tunnel diodes, varactors, fast recovery diodes, Gunn diode, IMPATT diodes, Zener diode, solar cells, ...). |  |  |
| Point out where and how you have to go into material parameters and technology to achieve the desired result |  |  |
4. Silicon: Special Properties and Emerging Technologies
| SOI - Methods for Wafer Production |  |  |
| Discuss the basic concept and the possible advantages Overview Nov. 02 |  |  |
| Discuss the various methods to produce SOI wafers, give pro and cons. |  |  |
| State of the art, outlook |  |  |
| SOI - Product and Technologies |  |  |
| Discuss possible products, pro and cons |  |  |
| Compare process flow for some examples; show improvement |  |  |
| Discuss special applications, e.g. MEMS |  |  |
| High k Dielectrics |  |  |
| Why? Overview Nov. 02 |  |  |
| What and How |  |  |
| Micromechanics and Microsystems |  |  |
| Basic concepts Optical MEMS |  |
| Key technologies |  |
| Key products, process integration, markets |  |
| Wafer Bonding |  |  |
| Principles, Methods, Applications |  |  |
| Optical Applications of Porous Silicon |  |  |
| Introduce porous Si and its optical properties |  |  |
| Discuss and systemize a range of applications (Waveguide, Bragg reflector, photonic crystals, sensors, ...) |  |  |
| Photonic Crystals and Semiconductors |  |  |
| Introduce the concept of photonic crystals |  |
| Basic theory, especially the differences to electrons in semiconductors |  |
| Review attempts to produce photonic crystals with semiconductors |  |
| Luminous Silicon |  |  |
| Elucidate current developments: Prevent defect recombination, Erbium doping, Si Nanocrystals, microporous Si, "spark" - processed Si, ... |  |  |
| Discuss possible mechanisms, possibilities, pro and cons. |  |  |
6. Basic Laser
| New Developments in Laser Techology |  |  |
| Present several special developments, e.g. VCSEL's, Quantum Cascade Lasers GRINSCH Lasers, Blue (GaN) Lasers,... |  |  |
| Discuss Advantages - Disadvantages; problems, state of the art, Specialites,.. |  |  |
| With respect to, wavelength, power, tunablitiy, ... |  |  |
7. LE Devices
| LED instead of Lightbulbs |  |  |
| Present the issue, argue the pros and cons of both light sources |  |  |
| Discuss the necessities for economical success |  |  |
8. Speed
| "Fast" Silicon |  |  |
|  | Present modern developments for fast Si devices, e.g. |  |  |
| Si - Ge, "Strained" Si, Si - C, low e and r (and of course device size). |  |  |
| Discuss state of the art, pro and cons. |  |  |
| HEMT |  |  |
| Present the HEMT concept |  |  |
| Discuss possibilites, limitations, state of the art. |  |  |
| Discuss key technologies. |  |  |
10. Specialities
| Semiconducting Polymers Literature: J. Mater. Res. Vol. 19, No 7, July 2004 |  |  |
| First presentation: General |  |  |
| Give short history, theory and chemistry. Scientifc details, ... |  |
| Second presentation: Organic Solar Cells |  |  |
| Basics, state of the art and outlook |  |
| Third presentation: Organic ICs |  |  |
| How to make them (cheaply), applications e.g. RFID |  |
| Silicon Carbide (SiC) |  |  |
| 1. Discuss the basic properties of the material Crystal growth, defects, material issues. |  |
| 2. Applications, SiC devices, special technologies, state of the art, outlook |  |
| Non-Silicon Solar Cells |  |  |
| Focus on CuInSe2 and related materials |  |  |
| Give properties of materials and specifics of technology |  |  |
| Discuss related materials, pro and cons, e.g. HgCdTe2 |  |  |
| Discuss the role of crystal lattice defects and of hydrogen passivation |  |  |
| Liquid Semiconductors |  |  |
| Define the term |  |  |
| Give examples, relate to amorphous semiconductors |  |  |
| Discuss uses |  |  |
| Peltier Elements and Thermoelectric Generators |  |  |
| Provide simple theory |  |  |
| Discuss desirable material properties; give efficiencies etc. |  |  |
| Discuss existing products and technologies, give outlook. |  |  |
| Liquid - semiconductor junctions |  |  |
| Theory of junction |  |  |
| Some practical examples (Si-HF system) |  |  |

| Team | Assistant General: Dr. Riemenschneider | Date
Solar Cell Topics Basic Literature
| Markets Technologies, Companies - an Overview |  |  |
| Solar Energy - what we get, we can use. |  |  |
| Humans and Energy: Where it comes from, how much we use, where we are headed. |  |  |
| Prices of Energy |  |  |
| Solar Cells - History, where it is headed |  |  |
| Literature: Photovoltaics the Basis for Sustainable Energy Systems and Industrial Innovations Die PV Szene heute - Technologie, Industrie, Markt The grand energy challenge 1 Photovoltaics the Basis for Sustainable Energy Systems and Industrial Innovations THE IEA PVPS PROGRAMME – TOWARDS SUSTAINABLE GLOBAL DEPLOYMENT OF PV Highlights of Europ. Conf. Soar Energy 2005 Barcelona |  |  |
| Basic Principles of Solar Cells and Solar Cell Moduls |  |  |
| Basics: IV, efficiency , fill factor, etc.. Essential material parameters (doping, life time, absorption,...). Add series resistance, add parallel resistance; discuss. Temperature dependence of efficiency etc. |  |  |
| Equivalent circuits, local variations of parameter. |  |  |
| Making Moduls. Problem of series resistance, shadowing |  |  |
| Literature: A solar cell primer |  |  |
| Crystaline Silicon Solar Cells |  |  |
| Monocrystalline high-efficiency cells. Mass product vs. world record winners. n- vs. p-doping. |  |  |
| Polycrystalline Cells. Making poly, making cells. Si shortage problem |  |  |
| Sliver Cells and other specialities. |  |  |
| Literature: Kristalline Silizium Solarzellen Cost comparison of large-scale crystalline and thin film PV systems THE CRYSTALCLEAR INTEGRATED PROJECT: next generation crystalline silicon technology from lab to production |  |  |
| The CIS Family |  |  |
| CuInSe2and related materials. What makes them special? |  |  |
| Give properties of materials and specifics of technology; Sputtering vs. CVD? |  |  |
| Specifics of technology: Series connection, stability, ... |  |  |
| Discuss the role of crystal lattice defects and of hydrogen passivation2 |  |  |
| Discuss related materials, pro and cons, e.g. HgCdTe systems |  |  |
| Literature: PILOT-LINE CIGSSE POWER MODULE PROCESSING AND QUALIFICATION AT SHELL SOLAR CIS THIN-FILM SOLAR MODULES – AN EXAMPLE OF REMARKABLE PROGRESS IN PV PROGRESS IN LOW-COST ELECTRODEPOSITION OF Cu(In,Ga)(S,Se)2 : THE CISEL PROJECT |  |  |
| Amorphous and Nanocrystalline Thin-Film Si Solar Cells |  |  |
| Discuss amorphous Si cells. What went wrong? |  |  |
| New developments. "Thin" and "Thick" Thin-Film cells. |  |  |
| Potential and specifics |  |  |
| Literature: RECENT PROGRESS IN AMORPHOUS AND MICROCRYSTALLINE SILICON BASED SOLAR CELL TECHNOLOGY |  |  |
| Tandem Cell, "Nano Cells and Exotica |  |  |
| Discuss tandem principle |  |  |
| Examples for tandem cell development |  |  |
| State of the art, potential for future |  |  |
| New concepts with e.g. nanodots |  |  |
| Literature: ALL-SILICON TANDEM CELLS BASED ON “ARTIFICIAL” SEMICONDUCTOR SYNTHESISED USING SILICON QUANTUM DOTS IN A DIELECTRIC MATRIX |  |  |
| Characterization Techniques |  |  |
| Characterizing a finished solar cell. Doing it with local information. Doing it in 1 s. |  |  |
| Characterizing materials (e.g. poly Si wafers or CIS layers). Which parameters are important? How to measure? How to predict the quality of cells made with the material? |  |  |
| Characterizing modules. Give some specific problems. |  |  |

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