Semiconducting Elements

Transistors

MOSFET
Here we are investigating the VI relation of a transistor using the MOSFET, from the below statement from wikipedia, we get the idea of the current being constant and the resistance of the transistor increases treamendously when the voltage increases, this effect still follow ohm's law's equation V = IR but in a special way that R is changing.

Power MOSFETs are at risk of thermal runaway. As their on-state resistance rises with temperature, if the load is approximately a constant-current load then the power loss rises correspondingly, generating further heat. When the heatsink is not able to keep the temperature low enough, the junction temperature may rise quickly and uncontrollably, resulting in destruction of the device.

P Type and N Type Semiconducting Materials

Is P Type Material positively charged?
Neutral unless you put static electricity onto it. P refers to the fact that conductivity comes from moving holes, which are positive but the electrons have not been removed from the material, they are just being held in the doping material. Having a doped material that conducts does not mean there is charge within the material, the amount of electrons and protons are still the same, just there are valence electrons floating around or vice versa....
http://in.answers.yahoo.com/question/index?qid=20070208022909AAGkOdU


Depletion Region of PN Junction Diode
http://www.ece.utep.edu/courses/ee3329/ee3329/Studyguide/Shockwave/PNjunctions/Demos/PNJunctionDiode.html#