Introduction

Question 1

What’s the conductivity of metals?

Answer 1

high (but almost uncontrolled) electrical conductance

Question 2

What is the conductivity of semiconductors?

Answer 2

easily controlled (over a wide range) electrical conductance.

you can control the properties and they are easily tunable.

Question 3

what are dielectrics (insulators)?

Answer 3

no electrical conductance

Question 4

What unit is conductivity measured in?

Answer 4

1/ resistivity = 1/ohm*m

Question 5

what is an optoelectronics?

Answer 5

both using electricity and light

Question 6

What is the feasibility of electric current for materials?

Answer 6

metals: yes
insulators: no
semi: yes

Question 7

What is the feasibility of light for materials?

Answer 7

metals: no
insulators: yes
semi: yes

Question 8

What is the feasibility of optoelectronics for materials?

Answer 8

metals: no
insulators: no
semi: yes

Question 9

Explain this image

Answer 9

scan using scanning tunneling microscopy STM represents electron concentration

Question 10

What is this?

Answer 10

A silicon ingot being pulled from a melt

Question 11

how are silicon ingots grown?

Answer 11

in labs in crystal drawers

Question 12

what is GaA used in?

Answer 12

high speed electronic devices and optoelectronics

Question 13

why isn’t silicon used in fast electronic devices

Answer 13

you can’t use silicon to absorb or emit light

Question 14

What is used to wire devices within a chip/integrated circuit?

Answer 14

metal interconnects

Question 15

What was the first commercial transistor?

Answer 15

silicon from Texas Instruments 1954

pocket radio

The Bipolar Junction Transistor BJT

Question 16

what does this demonstrate

Answer 16

demonstrates quantum nature of light. light is comprised of huge numbers of small particles

Question 17

why don’t particles have mass

Answer 17

they move with the speed of light

Question 18

do photons have mass? energy?

Answer 18

no mass, because it moves at the speed of light

yes energy, it has velocity

Question 19

what’s important about this table?

Answer 19

different materials for light emitting dyads.

the wavelength light column changes the different type of light

new type of material– new wavelength

Question 20

how do you convert from wavelength to Eg

Answer 20

wavelength = 1.24 /Eg

Question 21

What does LASER stand for

Answer 21

light amplification by stimulated emission of radiation

Question 22

what does the light look like in absorption, spontaneous emission, and stimulated emission?

Answer 22

Question 23

what happens during absorption

Answer 23

electron goes to the next level

Question 24

what happens during spontaneous emission

Answer 24

electron goes down to a lower level

it happens easily because electrons go down by themselves easily, and it releases a photon

Question 25

what is the difference in energy in versus out

Answer 25

energy of the photon

Question 26

what happens during stimulated emission?

Answer 26

it doesn’t dop down by itself, the stimulation is coming from the light

releases 2 photos, one from light one from emission

made by the photon

Question 27

what are three categories of lasers?

Answer 27

gas lasers

solid-state lasers

semiconductor lasers

Question 28

why are semiconductor lasers good

Answer 28

• small and compact
• you don’t need to have another source of light
• you inject an electron
• you take out the electron from the lower level and put in the top (introducing a positive charge basically)

Question 29

where is electrical current injection used

Answer 29

semiconductor lasers

Question 30

what is the most common pumping scheme

Answer 30

optical pumping

Question 31

What three categories are semiconductor lasers at the intersection of?

Answer 31

physics
optoelectronics
materials science