Emiola Banwo

Empathize with Emiola

This is a collection of my recent studies, deep reflections, and random thoughts. Read on and let me know what you think!

A (Top-Down) study of Solid-State Electronic Devices


Being a Computer Engineering student, this semester (Fall 2014) i'm enrolled in a class called Electronic Devices (EE 3310). As someone with an interest in electronics, I didn't know what to expect to learn in the class, but that I would surely love and enjoy it. It didn't turn out that way.

As strange as it seems, I learn new subjects best when taught from Top-Down - starting with high level concepts, then drilling down into the nitty-gritty details. However, this class was teaching solid state semiconductor physics in the opposite fashion, bottom-up; Starting from the atomic makeup of a cubic crystal, up to Metal-Oxide-Semiconductor field effect transistors (or MOSFETs). Needless to say, I was dumbfounded since the very beginning of this class, having seemingly found myself in a chemistry class. I didn't do well on the first exam due to a combination of hating the class and having a heavy course and extracurricular load which I held at higher priority.

Three weeks after midterms, it came time to take the second exam of the semester. Our professor informed us that all assignments and exams up until that point had only counted for a third of our overall grade, and that this next exam would count for another third. At this point, we had discussed up to Bipolar Junction Transistors (BJT), a relatively high-level concept in the domain we are exploring. From this high-level position back to everything low-level we had learned previously things we're starting to make sense to me. An example of high to low progression would be: this is what we would like to happen, this is what we would have to make, and this equation models how this will happen. A glimmer of hope. I spent time gathering resources, online and off, that what would help me study for the exam.

With other coursework and activities pressing,  I was left with 4 full days to study prior to the exam. My plan was to first learn all the concepts Top-Down, creating a detailed document of all the concepts with definitions and hierarchy. Second, was to find all the equations that modeled and related all the concepts. We were allowed a full page "cheat sheet" on the exam, so memorization wasn't needed. Next, I would go over homework problems that were assigned (which I initially didn't understand). At this stage of studying - a day before the exam -  some formulas would be marked-off that seemed unnecessary or too low level . Lastly, the day of the exam I created my cheat sheet and helped other students with questions or clarifications. 

Everything went as planned! In 4 days, I learned everything I needed to about Solid State Semiconductor physics, from the High-level of BJTs to the low-level of charge carrier generation, combination and structure within a crystal Lattice. I now love this subject, and am proud of my new-found "lens" of seeing the world of electronics. There's still a month left of the semester but I feel prepared and can't wait to take on MOSFETs.

If you're curious about learning about how your electronic devices work on a quantum level. Here is the beginning (read: high level) portion of that detailed document I referenced:

  • Semiconductor Physics for Solid State Electronics concerns the properties of Silicon and Germanium, elements which form a regular Crystal Lattice whose Energy gap may be analyzed by the Band Theory of Solids, such that the Population of the Conduction Band depends upon the Fermi Function of probability. 

  • Semiconductors may be Intrinsic Semiconductors (notably Silicon and Germanium) but they are limited to a very small Intrinsic Current, so most uses involve Doped Semiconductors (Extrinsic Semiconductors), in the form of P and N Type Materials (operating in Forward Bias or Reverse Bias), which can be used to fabricate P-N Junctions.

  • P-N Junctions are key to making Diodes and Transistors, the elemental components in electronic devices.

  • Semiconductor Physics has applications like Zener EffectLight Emitting Diodes(LED) and the Tunnel Diode. 

  • .......

I've created a document that is shared publicly, in it is the detailed explanation of all of the concepts stated above, minus formulas. Let me know what you think, if you need help or if a concept is described wrong in any way. 
Link: https://docs.google.com/document/d/1erto09Atf_hx2q0aQ3HC01_7sKZvYnSrLMC8QXFq3Qg/edit?usp=sharing

Emiola BanwoComment