Semiconductor Principles - General Questions (2)

Solid state devices were first manufactured during:

A P-N junction mimics a closed switch when it:

When is a P-N junction formed?

When and who discovered that more than one transistor could be constructed on a single piece of semiconductor material:

Which semiconductor material is made from coal ash?

Forward bias of a silicon P-N junction will produce a barrier voltage of approximately how many volts?

When an electron jumps from the valence shell to the conduction band, it leaves a gap. What is this gap called?

What can a semiconductor sense?