**Session –**

Autumn 2019

**Instructor –**

Pradeep Nair

**Course Content –**

Module 1: Introduction and Fundamentals Aim: To introduce the concept of band structure of common semiconductors and the associated terminology Contents Introduction Basics of QM Band structure of 1D cyrstals, concept of electron/hole, effective mass Crystal structure and Band-structure of common semiconductors

Module 2: Equilibrium carrier statistics Aim: Here we first consider an unperturbed semiconductor to derive estimates for the density of electrons and holes (remember, current through a device is influenced by carrier density). For this, as the dictated by QM, we need to worry about the density of available states and the probability of filling them. Once done for pure crystals, we will then consider the effect of uniform doping as well.

Contents Density of states Maxwell-Boltzmann and Fermi-Dirac distributions, concept of Fermi level Energy band diagram Equilibrium concentration of carriers, Doping, Temperature dependence

Module 3: Generation -recombination Aim: The electrons and holes in a semiconductor is in a state of dynamic equilibrium (under steady state conditions). Here, we will consider the basic phenomena involved in such process. Further, we will see how the semiconductor responds to simple excitation (note that to make use of device for any application, you need to perturb it, say through a voltage, to off-equilibrium).

Contents Band-Band, Trap assisted recombination Carrier modulation due to uniform illumination, detailed balance analysis, effective lifetime Quasi-Fermi levels

Module 4: Carrier Transport Aim: Here we will try to understand the response of carriers to external perturbations like electric field. We will derive a set of basic equations to self-consistent predict the behavior of a device.

Contents Drift,Diffusion, and Einstein relation Continuity equations (this involves both carrier transport and Generation-recombination) Drift-diffusion formalism for semiconductors Minority carrier diffusion equation and examples

Module 5: PN Junction diode Aim: Using the formalism developed in the previous model, we develop analytical models for the PN junction diodes. The results are then compared with experimental data and numerical simulations as well.

Contents Junction electrostatics Current-Voltage characteristics of short and long based diodes AC capacitance Applications: Solar cells, LEDs

Module 6: MOS Aim: Here, we develop predictive models for MOS capacitors and MOSFETs – the workhorse of modern IC technology. We will analyze current and future trends based on the results of the models developed.

Contents MOS capacitors: LF, HF Capacitance-Voltage Long channel MOSFET: Current-Voltage, DC biasing, AC equivalent circuit Scaling trends

Module 7: BJT Aim: Although BJTs are not as widely used, they offer a good test bed for the concepts learned so far. Again, we will develop appropriate models to understand the device operation.

Contents Electrostatics Device characteristics: DC , AC

**Prerequisite –**
None. Good knowledge of EE112 or EE101 can be very helpful.

**Feedback on the lectures –**
Sir was very enthusiastic to teach the course. His lectures were very thorough and explanatory. He moved on a slow pace keeping in mind that every student should understand. The lectures were more than enough for the course and no self-reading was required. The sir also gave practice problems which were later discussed by him or TAs in tutorial sessions. These tutorials ran parallel to lectures and since the course required a few practice problems thus they played a vital role. There were also “Food For Thought” questions which were for the student’s extra learning. Sir actively took doubts in the class and encouraged the students to give the answers to the questions he asked. He always laid emphasis on observing rather than just learning so there were many simulation exercises. There were weekly 15-20 min quizzes contributing to the revision of the content. The instructor was always enthusiastic enough to take feedback and improve.

**Feedback on Assignments/Tutorials/Exams –**

There were weekly quizzes which were mainly aimed to clear the concepts and keep a hold of the content. The questions in the quizzes were very similar to those discussed in the tutorials. The main aim of these quizzes was not scoring marks but clarifying the topics. These quizzes were generally easy and marks can be scored if silly mistakes are not made.

Since this course required solving problems thus tutorials were a major role to play. The tutorial problems were posted weekly and difficult problems were discussed by the TAs or the sir. The tutorials can be solved using the material covered in the class. The tutorials were having a moderate difficulty level.

There were simulation assignments given by the sir. Nanohub was to be used to simulate and ceratin observations had to be reported. The assignment was very easy and was meant to observe the changes in semiconductor properties with changes in several conditions.

Midsem was moderate whereas Endsem was slightly on the tougher sides.

**Difficulty (on a scale of 1-5 with 5 being very tough) –**

3

**Textbooks/References –**

Advanced Semiconductor DevicenFundamentals

**Softwares used –**

Nanohub simulation tools

Reviewed by Shailee Suryawanshi