Intro to Electronics CH's 19-26 Semiconductor Devices

Silicon has__________resistance than germanium at room temperature.

1000 times more

Transistors are usually given manufacturer model numbers that begin with:

2N.

Electron-hole pair

An electron and its corresponding hole or absence of electron in the semiconductor matrix.

What are 2 pentavalent impurities?

Arsenic & Antimony

Negative Temperature Coefficient

As temperature of a material increases it electrical resistance decreases

N type material

Electrons are majority carrier. Holes are minority carrier.

Pure semiconductor materials

Germanium (Ge) Silicon (Si) & Carbon (C)

Semiconductor materials

Have characteristics that fall between insulators and conductors.

When using semiconductors, what is the major problem that must be controlled?

Heat and the changes caused by heat.

What are 2 trivalent impurites?

Indium & Gallium

The Plastic Lead Chip Carrier (PLCC) IC packaging design uses:

J shaped leads.

The Small Outline Integrated Circuit (SOIC) packaging design uses:

L shaped leads.

When handling or using MOSFET's the following must be observed:

MOSFET leads must be kept shorted by storing them in conductive foam. all instruments, tools, hands must be connected to ground. MOSFET's must be installed or removed with the power OFF. (all of these.)

Active materials

Materials that need electrons to complete their valence shells.

If the channel region of a FET is doped and constructed using pentavalent impurities, the FET is called a:

N-channel FET.

What happens with a negative temperature coeffient?

Negative temperature coefficien means increase temperature=decrease in resisitance.

If the channel region of a FET is doped and constructed using trivalent impurities, the FET is called a:

P-channel FET.

Doping a semiconductor with trivalent impurities results in:

P-type material

Photoconductors can be constructed much like:

PN-junction diodes of clear glass or plastic. NPN junction transistors with a window. NPN FET's with a window. (all of these.)

One type of transistor which contains two P-regions that are separated by an N-type material is called a:

PNP transistor.

The type of transistor which contains P-type material as the emitter is called a:

PNP transistor.

Donor atom

Pentavalent atom that gives away extra electron in the semiconductor matrix.

What are the two semiconductor elements suitable for electronic applications?

SIlicon (Si) and Germanium (Ge)

What makes silicon more desirable to use than germanium?

Silicon has more resistance to heat than germanium.

Valence

The indication of an atom's ability to gain or lose electrons.

Doping

The process of adding impurities to a semiconductor material.

Covalent bonding

The process of sharing valence electrons.

How do active materials gain stability?

They must acquire electrons for their valence shells.

Acceptor atom

Trivalent atom that shares valence electrons with adjacent atoms creating holes.

Pentavalent

Type of impurity used in doping. Atoms have FIVE valence electrons. Makes N type material.

Trivalent

Type of impurity used in doping. Atoms have only THREE valence electrons. Makes P type material.

In a zener diode, the cathode is:

a Z shaped bar. indicated by a color band. reverse biased. (all of these.)

The symbol for a photodiode includes:

a bar for the cathode. two inward facing arrows. an arrow for the anode. (all of these.)

The principal differences between a junction field effect transistor and a bipolar junction transistor are:

a field effect transistor is a voltage operated device. a bipolar junction is a current operated device. their construction is completely different. (all of these.)

The LED when used in a working circuit must include:

a forward bias voltage above the barrier potential. a sufficient current flow to cause light. a protective series resistor to limit current flow. (all of these.)

A forward biased PN-junction requires:

a negative voltage source connected to N-material.

A forward biased PN-junction conducts a current when:

a negative voltage source is connected to N-material. a positive voltage source is connected to P-material. the voltage source exceed the barrier voltage. (all of these.)

The IC classification VLSI typically indicates:

a pc's main processor chip. a computer RAM or ROM memory chip. more than 15,000 interconnected components. (all of these.)

In order to perform voltage regulation using a zener diode, what other circuit component is required:

a series resistor.

The Flat Pack IC packaging design uses:

a thin molded plate. ceramic or high temperature materials. multiple wire leads. (all of these.)

Heat creates problems with semiconductor materials by

allowing electrons to break their covalent bonds.

The reverse current in a zener diode measures as a:

almost maximum value.

A hole represents

an absence of an electron in the valence shell.

Within a doped semiconductor material, there will be:

an equal number of mobile and ionic charges.

The symbol for the emitter part of a transistor may contain:

an outward going arrow. the capital letter E. an inward going arrow. (all of these.)

Integrated circuits that are classified as linear IC's are used for:

analog circuit applications. oscillators. amplifiers. (all of these.)

The opposite charges that build up on each side of a PN-junction create the:

barrier voltage.

Transistors are classified by the following method(s):

by type. by use. by material. (all of these.)

The bias voltage connected between the gate and source is:

called the EGS or just EG. is in the reverse bias direction. opposes a current flow. (all of these.)

Any temperature sensitive diode especially a zener diode, can be changed into a temperature compensated diode by:

connecting an opposite temperature coefficient diode in series with forward biasing.

In testing a zener diode with a Digital Multimeter, what tests can be performed:

continuity test. reverse resistance test. forward resistance test. (all of these.)

The size of the depletion region in a FET is:

controlled by EGS. increases with increases in EGS. decreases the output or drain current ID. (all of these.)

Impurities with five or more valence electrons are also known as:

donor atoms.

Holes constantly

drift towards the NEGATIVE terminal of the voltage source.

Each free valence electron and the resulting hole formed in a semiconductor material is known as:

electron-hole pair

The three parts or regions of a transistor are called:

emitter, base, collector.

Electrons in the outer band or shell of an element are characterized by their:

energy

As the frequency of light waves increases, it is noted that their:

energy decreases and wavelength increases.

Applying a voltage source to a pure semiconductor material results in:

free electrons moving to the positive terminal. holes effectively moving to the negative terminal. electron-hole pairs forming.

The symbol for a N-channel depletion mode MOSFET differs from a junction FET in that:

gate is a bar not an arrow.

The three parts or regions of a FET are called:

gate, source, drain.

Electrical activity in semiconductor material is

highly dependent on temperature.

Linear ICS are divided into types based on the construction techniques, the most popular being:

hybrid.

For a transistor to operate in the optimum part of its range, the emitter-to-base bias should be:

in the forward direction. high enough to overcome the barrier voltage. allow a reasonable electron flow. (all of these.)

The reverse bias condition causes the barrier voltage to seemingly:

increase in level.

An optocoupler is used in circuits principally because:

it provides a high degree of electrical isolation.

The IC classification MSI means:

less than 1500 interconnected components.

The IC classification SSI means:

less than 180 interconnected components.

Zener diodes are used in two different ways to control voltage; these are called:

line or input and load regulation.

Transistor leads can best be identified by:

looking them up in a transistor parts manual.

The main disadvantages of IC's are:

low voltage handling ability. low current carrying capability. high design costs depending on complexity. (all of these.)

Which of a diode's maximum ratings can be exceeded without causing damage to the PN-junction:

maximum forward current rating. maximum temperature rating. maximum reverse voltage rating. (none of these.)

A zener diode's maximum current rating is determined principally by its:

maximum power dissipation.

The best way to get accurate results in testing between the gate and source or drain of a MOSFET with an ohmmeter is:

measuring infinite resistance in both directions.

The IC classification LSI means:

more than 15,000 interconnected components.

Correct biasing for an NPN transistor is:

negative on emitter, positive on base, positive on collector.

The N-channel MOSFET operates in the depletion mode when the bias voltage is:

negative on the gate with respect to the source.

The principal differences between FET's and MOSFET's are:

no PN-junctions are formed. a thin gate insulating film is fabricated. a metallic gate structure is used. (all of these.)

Atoms with five valence electrons are called:

pentavalent materials.

Transistor packages are mostly made of:

plastic material.

A properly operating zener diode can be used to:

regulate a voltage. correct for load resistance changes. compensate for power line fluctuations. (all of these.)

The unique design feature of a zener diode needed for its operation is the:

reverse bias breakdown mode.

Materials whose molecules readily arrange themselves into crystal structures are held together by

sharing valance electrons. covalent bonding. full valence shells.

Physical advantages of semiconductors include which of the following:

size. weight. ability to operate in harsh environments. (all of these.)

Semiconductor material must have valence shells

that are half full.

The most popular style of diode is known as:

the axial lead.

In a typical PN-junction diode, the cathode is:

the bar or line symbol. indicated by a color band. the N-type material. (all of these.)

The symbol for a photovoltaic cell may include:

the battery drawing. the Greek letter lambda. two inward facing arrows. (all of these.)

A zener diode rated as having a negative temperature coefficient means that:

the breakdown voltage increases with temperature decreases. the breakdown voltage could be between 4 and 5 volts. the breakdown voltage rating is usually below 4 volts. (all of these.)

The area close to the junction of N- and P-type materials formed by majority carriers crossing the junction is known as:

the depletion region.

The conductivity of P-type and N-type semiconductor materials depends on:

the doping level.

For those MOSFET's with 3 leads, what device's parts are interconnected internally:

the source and the substrate.

The color and intensity of the light emitted by a LED depends on:

the value of the current flow. the color of the plastic case. the semiconductor material used. (all of these.)

The broken line on the enhancement type MOSFET indicates:

there is no structural connection from source to drain. there is no current flow normally. the normal condition without a signal is OFF. (all of these.)

Special precautions must be observed when handling and using MOSFET's because of the:

thin insulating film on the gate. high almost infinite gate input resistance. substantial input capacitance. (all of these.)

Electrons always flow

towards the POSITIVE terminal of the voltage source

A PN-junction diode is primarily:

unidirectional.

The most reliable method of testing FET's and MOSFET's is:

using a transistor tester that works in an operating circuit.