Reddit reviews Advanced Engineering Electromagnetics

That is a FANTASTIC reference book. Keep it forever because it will always be useful. IMHO, he doesn't even make an attempt to teach anything with that book, but it has earned a place on my bookshelf next to Paul, and Rhode&Schwartz's book on VNAs.

I'm loathed to recommend Balanis because I had so much trouble with that book, but it did cover waveguides reasonably well. Or at least, I think he covered waveguides better than he did boundary conditions and incident reflections.

In the end I wound up reading about 4 textbooks to get a good understanding during my first graduate EM course. I don't recall which they were anymore but I'm pretty sure all but Balanis were openly published and could be found again. I believe that I found one of the ones that I used under MIT's open courseware.

Solid State Electronic Devices by Streetman and Banerjee is everything you need to know semiconductor devices and the physics behind them.

Advanced Engineering Electromagnetics by Balanis covers E&M waves

I'd suggest going for a good Electromagnetics textbook. Balanis is pretty good. Looking at them as the radial form of sin and cos functions is what really made them make sense to me.

I would recommend you stick to books for EEs, rather than physics (Griffiths and Jackson are physicists). Its all the same stuff obviously, but the focus, methods and notation is rather different (e.g e^jwt vs e^-jwt) and and that will be confusing when you are staring out. I would get the book assigned by your professor, and if you want to go more in depth, check out:

Balanis Advanced Engineering Electromagnetics
and
Harrington Time-Harmonic Electromagnetic Fields

These books are classics and are oriented at a first year graduate student, but would be good references to augment your undergrad course material. They will go into a bit more detail and mathematical rigor, and if you're motivated and interested, I think they would be beneficial.