Optical Basics _MEMS

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1 ROCHESTER INSTITUTE OF TECHNOLOGY MICROELECTRONIC ENGINEERING Optical Basics _MEMS Dr. Lynn Fuller Webpage: 82 Lomb Memorial Drive Rochester, NY Tel (585) Fax (585) Department Webpage: Optical_Basics_MEMS.ppt Page 1

2 OUTLINE Light Sources Light Detectors Optic Components Mirrors Light Emissive Devices Light Modulators References Homework Page 2

3 SPECTRICAL DISTRIBUTION OF SOLAR RADIANT POWER From: M icromachined Transducers, Gregory T.A. Kovacs Page 3

4 BLACK BODY, AM0 AND AM1.5 From: Solar Cells, M artin A. Green, Prentice Hall Page 4

5 BLACK BODY RADIATION From: M icromachined Transducers, Gregory T.A. Kovacs From: Solar Cells, M artin A. Green, Prentice Hall Page 5

6 HOT FILIMENT BLACK BODY LIGHT SOURCES Dave Borkholder Senior project µm MOVIE 100 µm Page 6

7 EMISSION SPECTRA OF THE Hg VAPOR BULB 1.0 i-line, 365 nm g-line, 436 nm 0.5 h f e Wavelength (nm) Page 7

8 LED IV CHARACTERISTICS Light Emitting Diode -LED I D Light Flat n - V a + p LED 2.0 V D Page 8

9 LIGHT EMITTING DIODES (LEDs) Electron concentration vs distance x Light Space charge Layer Hole concentration vs distnace Light x P-side N-side In the forward biased diode current flows and as holes recombine on the n-side or electrons recombine on the p-side, energy is given off as light, with wavelength appropriate for the energy gap for that material. λ = h c / E h = Plank s constant c = speed of light Page 9

10 LEDs SFH4110 SEP8736 SEP8736 Page 10

11 RIT S FIRST LED GaP wafers with n-type epilayer, add gold metal, dice and wire bond to RIT thick film ceramic package. Page 11

12 RELATIVE LUMINOSITY VS WAVELENGTH Human eye perceives 550nm (green-yellow) as the brightest, the relative luminosity of other colors is give above Page 12

13 PHOTODIODE space charge layer B - + B- + B- p-type B - I P+ P+ B - B - B - P+ B - B - - P+ ε - + P+ P+ + P+ electron and hole pair - P+ Phosphrous donor atom and electron P+ Ionized Immobile Phosphrous donor atom B - Ionized Immobile Boron acceptor atom B- + - P+ - P+ Boron acceptor atom and hole - P+ n-type - P+ Page 13

14 WIDTH OF SPACE CHARGE LAYER Width of space charge layer depends on the doping on both sides and the applied reverse bias voltage and temperature. Page 14

15 ADSORPTION VERSUS DISTANCE V I n p I + V - I No Light More Light Most Light V M.A.Green and Keevers φ(x) = φ(0) exp -α x Find % adsorbed for Green light at x=5 µm and Red light at 5 µm Page 15

16 CHARGE GENERATION vs WAVELENGTH E = hν = hc / λ h = e-34 j/s = (6.625 e-34/1.6e-19) ev/s E = 1.55 ev (red) λ1 λ2 λ3 λ4 + + E = 2.50 ev (green) B - B- B- p-type B - E = 4.14 ev (blue) P+ B - B - B - P+ n-type P+ - P+ ε B - B P+ P+ P+ + P+ - P P+ - P+ I To generate e-h pair in silicon we need E > Egap E > 1.12 ev Page 16

PN JUNCTION DESIGN FOR PHOTO DIODE 100% 10 17 10 15 60%

17 PN JUNCTION DESIGN FOR PHOTO DIODE 100% µm 1µm 2µm 3µm 4µm Space Charge Layer Page 17

CHARGE GENERATION IN SEMICONDUCTORS From: M icromachined Transducers, Gregory T.A. Kovacs E = hν = hc / λ What wavelengths will not generate e-h pairs in silicon.

18 CHARGE GENERATION IN SEMICONDUCTORS From: M icromachined Transducers, Gregory T.A. Kovacs E = hν = hc / λ What wavelengths will not generate e-h pairs in silicon. Thus silicon is transparent or light of this wavelength or longer is not adsorbed? Page 18

19 PIN, AVALANCE PHOTODIODES (APD) p-side n-side Intrinsic P I N W1 0 0 W2 PIN and Avalance photo diodes (APD) are made with an intrinsic (almost zero doping) layer between the N and P layers. The depletion layer is increased by the width of the Intrinsic layer. Avalance diodes are the same structure but used with large reverse bias (>100 volts) that creates large electric field in the space charge layer that can accelerate the electrons to velocities high enough to cause ionizing collisions giving a multiplication of carriers. Each photon can generate hundreds of electron hole Microelectronic pairs. Engineering Page 19

20 PIN, AVALANCE PHOTODIODES (APD) Page 20

21 PHOTOMULTIPLIER V V Vout hv V V R Photo Multiplier Tube (low work Function) Page 21

22 CHARGE COLLECTION IN MOS STRUCTURES E = hν = hc / λ h = e-34 j/s = (6.625 e-34/1.6e-19) ev/s + V λ1 λ2 λ3 λ4 thin poly gate E = 1.55 ev (red) E = 2.50 ev (green) E = 4.14 ev (blue) electron and hole pair - + B B depletion region B - ε p-type B Page 22

23 PHOTO DETECTORS From: M icromachined Transducers, Gregory T.A. Kovacs Page 23

24 TRANSMISSION PROPERTIES OF OPTICAL GLASS Transmission, % Quartz, 90 mil White Crown Glass 60 mils Borosilicate Glass 60 mils Green Soda Lime Glass 60 mils Wavelength (nm) Page 24

25 SOLAR CELL TUTORIAL SOME TERMS AND DEFINITIONS: Air Mass amount of air between sun and solar cell. In space AM=0 at the equator at noon AM=1, if the sun is arriving at an angle θ, AM=1/cos θ. AM1.5 is the standard for most solar cell work in USA and gives a sum total of 1000w/m2 over the entire spectrum of wavelengths from 0.2um to 2.0um Efficiency is the ratio of the power out of a solar cell to the power falling on the solar cell (normally 1000w/m2 with the AM1.5 spectrum) Since Si solar cells can not absorb much of the infrared spectrum from the sun, and other factors, typical efficiencies are limited to 26-29% for basic silicon solar cells. Quantum Efficiency normalized ratio of electrons and holes collected to photons incident on the cell at a single wavelength, given in %. FF Fill Factor, a figure of merit, the squareness of the diode I-V characteristic in 4 th quadrant Microelectronic with light Engineering falling on the cell. Page 25

26 SOLAR CELL 16000um x 16000um Ellen Sedlack 2011 Page 26

27 I-V CHARACTERISTICS OF SOLAR CELL Ellen s Photo Diode Von = 0.6 volts Rseries = 1/slope = 1/0.129 = 7.75ohms Is = 1.48uA (in room light) Page 27

28 SOLAR CELL QUANTUM EFFICIENCY 93% between 550nm and 650nm Ellen Sedlack 2011 Page 28 Yushuai Dai

29 SOLAR CELL TUTORIAL Voc - open circuit voltage Isc short circuit voltage Vmp Voltage at maximum power Imp Current at maximum power FF FF = VmpImp/VocIsc No Light Most Light Isc Vmp Diode I vs V Max Power Power = I x V Imp I Voc + V - V I Page 29

30 SOLAR CELL POWER EFFICIENCY AM 1.5 Light Source Zachary Bittner Ivan Puchades Page 30

POWER, EFFICIENCY, Isc, Voc 0.00E+00-2.00E-04 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.00E+00-1.00E-04-4.00E-04-2.

31 POWER, EFFICIENCY, Isc, Voc 0.00E E E E E E E E E-04 J 4_G4 P 4_G4-1.00E E E E E E-04 Page 31

32 THERMOPILE SENSOR Page 32

RIT THERMOPILE SENSOR Output voltage vs Input power for wafer 4

2 Kohms Output Voltage(uV) 250 200 150 100 50 0-50 0 0.1 0.2 0.3 0.

33 RIT THERMOPILE SENSOR Output voltage vs Input power for wafer Die 3, R= 12.2 Kohms Output Voltage(uV) Input power(mw) Die 5, R= kohms Die 6, R= kohms Die 7, R= 15 Kohms Usha Kuppuswamy, 2005 Page 33

34 FIBER OPTIC COMPONENTS Page 34

35 LASER AND FRESNEL LENS Page 35

36 OPTICAL SYSTEM Fresnel Lens Page 36

37 HINDGE Page 37

38 SELF ASSEMBLY Page 38

39 ELECTROSTATIC COMB DRIVE Movies at Page 39

40 ELECTROSTATIC COMB DRIVE MIRROR Movie Page 40

41 ELECTROSTATIC MIRROR Page 41

42 MIRRORS MOEMs - Micro Optical Electro Mechanical Systems Lucent Technologies Lambda router, 256 mirror fiber optic multiplexer Page 42

43 TORSION - MIRROR Inflection point Movable mirror poly 0 Substrate poly 1 Torsion Hinge Micro-mirror Perspective View Page 43

44 POLYIMIDE ON HEATER Movie Jeremiah Hebding Page 44

45 THERMALLY ACTUATED MEMS MICRO MIRROR Page 45

46 DIGITAL MIRROR LIGHT PROJECTION SYSTEM Page 46

47 TORSIONAL MIRRORS Page 47

48 TI MICROMIRROR PROJECTOR Page 48

49 TEXAS INSTRUMENTS DIGITAL PROJECTION PRODUCTS Movie Page 49

50 DXtreme PRO1 Page 50

51 FIELD EMISSION TIPS FOR FLAT PANNEL DISPLAYS 1 µm Alex Raub, 1995, now at National Semiconductor Santa Clara, CA Page 51

FIELD EMISSION FLAT PANNEL DISPLAYS Transparent Si Seal/Plug 2 Window O Vacuum Chamber Control Gate Insulator Emitter Low Voltage Phosphor Substrate Micro-encapsulated Chamber.

52 FIELD EMISSION FLAT PANNEL DISPLAYS Transparent Si Seal/Plug 2 Window O Vacuum Chamber Control Gate Insulator Emitter Low Voltage Phosphor Substrate Micro-encapsulated Chamber.900 Integrated Phosphor Field Emission Device Color Chart of AVT Phoshors YELLOWISH GREEN GREEN BLUISH GREEN BLUE GREEN GREENISH.200 BLUE BLUE.100 PINK RED PURPLISH RED REDDISH PURPLE Page 52

53 REFLECTIVE MECHANICAL LIGHT MODULATOR Page 53

54 RIT LIGHT MODULATOR - SENIOR PROJECT Sushil Shakya Page 54

55 REFERENCES 1. Micro Spectro Photometer by Marion Jess, Carl Duisberg Gesellschaft e.v., Fachhochschule Koln, Germany, August Fundamentals of Microfabrication, Marc Madou, CRC Press, LLC, Scientific Measurement Systems, Inc., 2527 Foresight Circle, Grand Junction, CO Micromachined Transducers, Gregory T. A. Kovacs, McGraw-Hill, Solar Cells, Martin A. Green, Prentice-Hall Page 55

56 HOMEWORK OPTICAL BASICS FOR MEMS 1. If the human body is thought of as a black body light source. What types of optical detector will be able to sense a human by sensing its IR emission? Explain. 2. Look up the Texas Instruments Digital Light Projector products. What is the cost of a developer kit for some of their projection products. 3. Visit the following web sites and discuss one product of interest for each Page 56

Diode Sensor Lab. Dr. Lynn Fuller

Diode Sensor Lab. Dr. Lynn Fuller ROCHESTER INSTITUTE OF TECHNOLOGY MICROELECTRONIC ENGINEERING Diode Sensor Lab Dr. Lynn Fuller Webpage: http://people.rit.edu/lffeee 82 Lomb Memorial Drive Rochester, NY 14623-5604 Tel (585) 475-2035 Fax