Course: ELE208
Instructor: Gmachl
F 2015

Description of Course Goals and Curriculum

ELE 208 is one of the four core electrical engineering courses (electrical engineers must take ELE 208B), usually taken in the Fall of sophomore year in conjunction with ELE 206 (digital logic design). It covers basic semiconductor physics and a broad range of semiconductor devices (some of which students will fabricate in the labs), along with basic fabrication techniques and applications of semiconductor devices in the real world. The two sophomore Fall electrical engineering classes complement each other well: ELE 208 discusses the physical basis of semiconductor devices such as transistors, while ELE 206 combines transistors to build logic gates, basic processors, and a programmable CPU. Most universities teach semiconductor devices in later years, as it usually requires significant knowledge of solid-state physics. However, Prof. Gmachl (Claire) teaches this course from a less physics-centered perspective, requiring only basic physics (the foundational engineering physics requirements) and an intuitive understanding of quantum mechanics, which she teaches in the first few weeks of class. Claire’s aim in this course is twofold. (1) Depth in the fundamentals of semiconductor devices: the quantum mechanics underlying band structure, carrier distribution and transport in bulk semiconductors, junctions between semiconductors and with metals, and the basic function of the field effect transistor. (2) Breadth in the variety of semiconductor devices: various types of diodes, photovoltaic cells, transistors, and their applications to areas such as biosensing, solar cells and digital circuits.

Learning From Classroom Instruction

Since there is no assigned textbook and lectures are not recorded, attending lectures is critical for doing well in ELE 208. In the past, Claire has also handed out Lindt chocolate truffles in lecture to simulate carrier interactions in semiconductors and to motivate lecture attendance. Lectures will alternate between the conventional presentational format and flipped lectures, but will consistently be highly interactive. To get the most out of each lecture, students should come prepared with questions about new material (for flipped lectures) or previous material. This is beneficial for everyone in class, since most of the class will be struggling to understand particular details about how the physics works. This question-and-answer format serves to help consolidate a working understanding of the underlying physics or what is happening in lab, which is particularly important since the class does not develop the mathematical or physical foundation to derive the answers to intuitive questions. The optional precepts are focused on consolidating conceptual understanding (students should again come prepared with questions). The preceptors will also be willing to help with particular problem set questions, and data analysis and writing for the two conference abstracts based on the labs. The labs are perhaps one of the highlights of ELE 208. Since the lab sections tend to be very small (at most around 8 students), there is a lot of time when students can ask questions about lecture material and how it links with what is being done in lab. The labs are designed to expose students to what it is like to work in a semiconductor devices lab, and are generally very enjoyable without being difficult. Because of the nature of device fabrication, the TAs will often have to perform additional processing between weeks that cannot be done in the allotted 3 hours. Students also learn to take detailed notes in their lab notebooks, which will be important for the conference abstracts that are based on the labs.

Learning For and From Assignments

The graded assessment in this course consists of: problem sets (and quizzes beginning Fall 2016), two conference abstracts, a midterm exam and a final exam. Problem sets are designed to consolidate a working understanding of course material. They are generally based on concrete application of the concepts and tools learned in lectures and labs, and help prepare for the midterm and final exams (the exams can be thought of as a collection of problem-set-style questions). As with any other classes with problem sets, work in groups and attend precepts for help with particular ambiguities or questions. Claire is generally relatively generous with extensions (except for Dean’s Date), but this has led students in previous years to pull heavy all-nighters to finish all their procrastinated problem sets before Dean’s Date. To learn from problem sets, students should ensure that they truly understand the material, so that the homework can become an exercise of application and consolidation rather than a floundering attempt to write something down on a piece of paper. Upon receiving feedback, if you realize that you do not understand the material or that your understanding was flawed, talk to the TAs in precept or ask for office hours so that you can ask questions. It is important that students make sure that they have a firm foundational understanding of the fundamental principles. For the exams, much of the same advice as above still applies. To prepare for the exams, students should briefly overview the material to see if they have a good functional understanding of the material, and then review past problem sets and do as many practice exams as possible. Claire prefers to test students on material that they are expected to know from what they have covered in the course. The conference abstracts aim to introduce students to scientific writing and conversation in the scientific community. Thus in the style of a real conference abstract, students are expected to individually write a two-page presentation of the results obtained in the lab, including a brief abstract, and the introduction, methods, results and discussion sections that are typical to a scientific paper. Students are also expected to analyze the data obtained in the lab (which are designed in such a way that they can be seen as a simple scientific experiment—for example, what thickness of a particular layer of an organic solar cell gives an optimal power conversion efficiency?) and produce “publication-quality” figures. Although this can sound daunting, starting at least a week or two before the deadline will spread out the work required, and the TAs will hold frequent office hours to help with data analysis and writing. The feedback from the first conference abstract will also inform the necessary changes for the second conference abstract.

External Resources

There is no assigned textbook for this course, since most standard textbooks on semiconductor devices are heavy on the underlying condensed matter physics. The Friend Center Library has at least one section dedicated to books covering semiconductor fundamentals and the principles of semiconductor devices, including a few good books that are relatively light on the physics and math. If you are interested in a more theoretical ground to supplement the concepts taught in class, Marius Grundmann’s The Physics of Semiconductors and Sze and Ng’s Physics of Semiconductor Devices are useful texts. These can be used to supplement lecture material, but should not replace going to the lectures themselves. There are also some very helpful online resources and references:

What Students Should Know About This Course For Purposes Of Course Selection

ELE 208B is required for electrical engineers in their sophomore year. Prospective electrical engineering majors should seriously consider taking this course for a taste of the quality of teaching in the ELE department and the community and camaraderie in the ELE cohort. ELE 208A is offered as an STL for non-STEM students.
Electronic and Photonic Devices

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