Elec 06-01 to Elec 06-04 Semicon

At very high temperatures the extrinsic semiconductors become intrinsic because

• drive in diffusion of dopants and carriers
• band to band transition dominants over impurity ionization
• impurity ionization dominants over band to band transition
• band to band transition is balanced by impurity ionization

To forward-bias a diode

• the anode voltage must be positive with respect to its cathode
• the anode voltage must be negative with respect to its cathode
• the cathode voltage must be positive with respect to its anode
• Either A or B

When a voltage is applied to a semiconductor crystal then the free electrons will flow.

• towards positive terminal
• towards negative terminal
• either towards positive terminal or negative terminal
• towards positive terminal for 1 μs and towards negative terminal for next 1 μs

A diode is a

• unidirectional device
• linear device
• nonlinear device
• Both A and C

Avalanche voltage is routinely exceeded when a P-N junction acts as a:

• Current rectifier
• Variable resistor
• Variable capacitor
• Voltage regulator

Of the following, which material allows the lowest forward voltage drop in a diode?

• Selenium
• Silicon
• Copper
• Germanium

A semiconductor, such as silicon, has an electron valence of

• +/- 4
• -7
• 1
• Zero

A disadvantage of gallium-arsenide devices is that:

• The charge carriers move fast
• The material does not react to ionizing radiation.
• It is expensive to produce
• It must be used at high frequencies

At room temperature the current in an intrinsic semiconductor is due to

• holes
• electrons
• ions
• holes and electrons

An unimportant factor concerning the frequency at which a P-N junction will work effectively is:

• The type of semiconductor material
• The cross-sectional area of the junction
• The reverse current
• The capacitance with reverse bias