Invited Talk - Bilaspur Univ

Design and Fabrication of the Guided Wave Devices at North Maharashtra University, Jalgaon D. K. Gautam Department of Electronics, North Maharashtra University, Jalgaon – 425 001(MS) INDIA D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Present trends of Optoelectronics

In India Designing, modeling and analysis of lasers and other devices are being carried out

In abroad Standardization in design,analysis and fabrication Optoelectronics Integrated circuit

Optimization of Optic fibers Optoelectronic materials thin films Device fabrication is being carried out at few places

Micro-machineries, short wave length lasers, optical computing Applied opt-electronics equipment Guided wave remote controlled automatic equipments

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Optical Communication Networks are being installed in India

Inevitable need for the developing the

INDEGENEOUS technology for Fabricating the components required for the communication networks

Cost Effectiveness D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Various Components required for the networks

Passive Power Splitters / Combiners Modulators / switches Multi/Demultiplexers Isolators

Active Laser Diode Amplifier LED

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Next Generation Computers and Integrated Circuits Demand for

Further Miniaturization for Increased Speed Higher Capacity That Needs

Tighter Confinement of Light New class of Devices

Photonic Crystal Devices D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Research & Development strategy at N.M.U.

Department of Electronics

First Tire

Second Tire

Third Tire

Design & Development Laboratory

Sophisticated Clean Room

Mass Scale Production facilities

Indigenously Developed Software Tools

Indigenously Developed Fabrication Machines

Characterization tools

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Department of Electronics, North Maharashtra University Established 10 years ago One of the Pioneer Institutions to Initiate the work related to optical guided wave devices

Capable of Design

Fabrication

Some Fabrication Facilities have been developed already, Work is in progress to develop other facilities

Active / Passive Devices D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

CAD Tools CAD Tools Based on BPM and FDTD Applicable to the Passive Devices:  Optical Waveguide  Waveguide Transitions, Bends, Junctions  Optical Multi/demultiplexer

Tools for Quantum Well Structures CAD Tools for the design of the Laser diode  Blue Laser Diode  GaN/AlGaN Heterostructure Laser Diode  ZnO/MgZnO Heterostructure Laser Diode

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Fabrication Infrastructure Available Clean room Photolithography facilities Chemical Draft Indigenously Developed Machines Characterization Laboratory Communication Laboratory

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Design Group

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Rib Waveguide Design w t

GT

Upper clad layer dh Guide layer

SiO2 buffer layer Silicon Substrate

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

w d h

Effective Index Method Applied to the Rib Waveguide Structure

Non Guiding region

GT

Guiding region

Non Guiding region

STEP I Air

Air

Air

Upper Clad

Upper Clad

Upper Clad

Guiding Film

Guiding Film

Guiding Film Lower clad

Guide I

STEP II

Lower clad

Lower clad Guide II Clad

Guid e

Nef1

Guide III

Clad Nef1

Nef2 Guide IV

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Main Equations used to Implement the Beam Propagation Algorithm e( x, y , z 0 ) = ∑a n E n ( x, y ) n

an =

+∞

∫ ∫ e( x , y , z

0

) E n ( x, y )

Decomposition to the Fourier Components

−∞

e( x, y, z 0 + ∆z ) = ∑ a n E n ( x, y ) exp(− jk n ∆z ) n

Propagation in Fourier Domain

Inverse Fourier Transform  − jk 2  E1 ( x, y, z 0 + ∆z ) = e( x, y, z 0 + ∆z ) exp  ∆n   2n0 

Correction for the perturbation in Refractive Index

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Our Tools Applied for the Design of the Directional Coupler Based Demultiplexer λ2

w s λ1,λ2

Guide I Guide II

W=waveguide width S=separation between the waveguides Advantage: Easy Fabrication Method

λ1

Bpm simulation results for the propagation of two wavelengths through the demux

λ1 = 1.3 μm λ2 = 1.304 μm Guide Separation = 2.5 μm Guide Thickness = 4.4 μm Rib Width = 9 μm Rib Height = 2 μm Clad Thickness = 2 μm Device Length = 7.3175 cm

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Hetero-structure Laser Design

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Physical Equations Electrical Equations

Optical Equations

Poisson’s Equation

Wave Equation

Continuity Equations for electrons and holes

Rate Equation for Photons

Current density Equation Output Characteristics D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Blue Laser Structure Used for the Analysis Y

x

p-contact

Upper clad Active layer

Lower clad n- Substrate n-contact

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Structural Parameters used for Analysis Layer

Thickness in nanometer

Doping Concentration in cm-3 .

Refractive Index

Substrate

1180

3 * 1018

3.6

767

7 * 1017

2.5878

13 %

17 %

50

1.7 * 1016

2.78

0 %

3 %

138

7 * 1016

2.5878

13 %

17 %

GaAs

Lower clad

% of Magnesium

−

% of Sulphur

−

ZnMgSSe

Active layer ZnSSe

Upper clad ZnMgSSe

Device width: 60 micron Channel width: 5 micron Channel depth: 0.5 micron

Physical Parameters Used for the Analysis Physical parameter Electron mobility Hole mobility Electron affinity Electron life time Hole life time Concentration in active layer Energy band gap Cavity length Reflectivity of each facet Thermodynamic temperature

value 600 cm2/volt-second 30 cm2/volt-second 3.9 electron volt 5 nanosecond 5 nanosecond 1.7 * 1016 cm-3 . 2.7 electron volt 700 microns 0.237 3000K

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Plot of Intensity(relative) verses Wavelength 1 0.9

Intensity (relative)

0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 503

505

507

509

511

513

Wavelength (nanom eter)

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Current verses Voltage Characteristics 350

Current (m illiam pere)

300 250 200 150 100 50 0 3.55

3.6

3.65

3.7

3.75

3.8

Voltage (volt)

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Plot of Output Power verses current 19.75

Pow er (m illiw att)

15.8

11.85

7.9

3.95

0 0

50

100

150

200

250

300

350

Current (milliampere)

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Field Intensity Distribution in X-direction 1 0.9

Intensity

0.8 0.7 0.6 0.5 0.4 0.3 5

15

25

35

45

55

Distance X (micrometer)

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Field intensity distribution in Y-direction Active layer

1

Substrate

0.9 0.8

Upper clad

Lower clad

Intensity

0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 700

1000

1300

1600

1900

2200

2500

Distance Y(nanometer)

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Analysis of optical field confinement

Upper Clad

ncu

Y Active Layer nf Lower Clad

Y

Nl

Nm

Nr

ncn

X X

Waveguide structure used for the light confinement in the vertical direction.

Waveguide structure used for the light confinement in the horizontal direction

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Full width of half maximum of field spreading as a function of channel width at 507 nanometer

Full w idth at half m axim um

35 30 25 20 15 10 5 0 0

5

10

15

20

25

30

35

Channel width (micron)

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Effective refractive index variation with the channel width 2.60527 2.605265

Effective index

2.60526 2.605255 2.60525 2.605245 2.60524 2.605235 0

5

10

15

20

25

30

35

Channel width (micron)

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Photonic Crystal Device Design

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA



WHAT IS PHOTONIC CRYSTAL?





Photonic Crystal - Photonic crystals are microstructured materials in which the dielectric constant is periodically modulated on a length scale comparable to the desired

wavelength

of

operation

and

in

which

electromagnetic waves of desired frequencies are forbidden.

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Why Photonic Crystal ? Most Important Points for today's VLSI/ULSI and Communication Technology :  Speed – Photonic crystals uses photons hence speed is greater than electro-optical devices.  Information carrying capacity – Photonic crystals uses photons hence information carrying capacity is greater.  Size – Photonic crystals has the dimensions of nano-sizes hence very compact size devices are possible.  All-optical IC’s – All-optical IC’s can be developed because using photonic crystals various devises can be fabricated such as lasers, filters fibers, multiplexer/demultiplexer,

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Semiconductor Semiconductor crystal crystal Periodic Potential Due to Periodic Atomic Lattice Bragglike diffractio n from atom Forbidden Gap for electrons

Photonic Photonic crystal crystal Periodic Potential Due to Lattice of macroscopic dielectric media Braggscattering at the dielectric interfaces Forbidden band gap (Photonic band gap) for photons

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

One dimensional photonic crystals

z

y x

Periodic in one direction

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Two dimensional photonic crystals z

A)

y x

B) Periodic in two direction

A) Dialectic rod PC with triangular lattice - lattice constant 700 nm, rod diameter 500 nm, rod height 3.9 µ m. B)

Air column PC with triangular lattice - lattice constant 580 nm, column radius 430 nm, column height 4.2 µ m.

(Obtained by Reactive ion etching of Si)

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Three dimensional photonic crystals

z

y x

Periodic in three direction

d w Logpile type PC –

Facets of a Si

d = 4.2 µ m,

inverted opal.

w = 1.2 µ m PBG is in infrared range

PBG Range

88% infiltration- 1.40 - 1.48 µ m 100% infiltration- 1.46 - 1.55 µ m

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Defects in Photonic Crystals



Point Defect



Line Defect

Resonant Cavity

Waveguide

(Traps Light)

(Transports Light)



Planer Defect

Perfect Dielectric mirror (Reflects Light)

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Fabrication Group D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

High growth rate techniques FHD

Sol-gel

PECVD

1. High growth rate 2. Porous Films 3. Poor uniformity 4. High temperature process 5. Annealing needed

1. High growth rate 1. High growth rate 2. Porous film 2. Dense film 3. Poor uniformity 3. Good uniformity 4. Low temperature 4. Low temperature process process 5. Annealing needed 5. Annealing not required 6. Useful for 6. Cannot be used in microelectronics microelectronics

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Chemical Vapor Deposition PECVD Sr. Properties APCVD LPCVD Techniques No. 300-500

500-900

100-350

Materials

SiO2

Poly-Si, SiO2, Si3N4, SiOxNy

Si3N4 , SiO2, SiOxNy

03.

Particles

Many

Few

Many

04.

Film Properties

Good

Excellent

Excellent

05.

Advantages

Simple reactor, Fast Deposition,

Excellent purity and uniformity

Low temp, Fast deposition

06.

Disadvantages

Low deposition rate

Chemical and Particulate contamination

07.

Applications

Poor step coverage & particle contamination Passivation, Insulation

Gate metal, Passivation, Insulation

Final Passivation, Insulation

01.

Temperature (oC)

02.

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Conventional CVD Technique Use of Silane

Dichloro - Silane • Toxic • Explosive • Pyrophoric • Corrosive

Solution is

Dangerous in handling

TEOS Extra Safety Measures required More Deposition Cost

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

TEOS-CVD Deposited films Show

Advantages

 TEOS is non  Excellent toxic uniformity  Non  Conformal step Pyrophoric coverage  Stable, inert  Good film liquid properties used in bubbler Reaction Handling is [Si(OC2H5)4] + O2 =easy SiO2 + by products D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Why SiO2 Films for Optical Devices?  Matured Process Technology  Refractive Index matches with the Optical Fiber  Minimizes the coupling losses  Polarization independent operation  Easy Fabrication  High integration capacity  Low manufacturing cost

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Why Si3N4 and SiOxNy Films? Superior material properties like:  High density,  High electrical resistivity,  Resistance to sodium ion,  Moisture permeation,  High thermal stability  Adjustable refractive index  Adjustable film stress D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Optimization of process parameters Flow rate Chamber pressure Substrate temperature TEOS temperature Reactor geometry Material of electrode Inter electrode spacing Electrode type

Growth rate

RF Power Residence time

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Processing Parameters Sr. No.

Process parameter

Physical value

1

Chamber Pressure

1 Torr

2

TEOS flow rate

3

O2 flow rate

4

TEOS Bubbler temp.

450 C

5

RF power

40 W

6

RF frequency

7

Substrate temperature

3 SCCS 15 SCCS

13.56 MHz 300 0 C

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Thickness Profile of SiO2 Films by PECVD

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Refractive Index Profile of SiO2 Films by PECVD

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

FTIR Transmittance spectrum of SiO2 Films by PECVD

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Transmittance Spectra of SiO2 films by PECVD S.N.

Si-O-Si stretching (cm-1 )

Si-O-Si bending (cm-1 )

Si-O-Si rocking (cm-1 )

FWHM

Authors

01

1070

810

450

88

L. Zajickova et al

02

1074

820

---

92.8

Ying-Chia CHEN et al

03

1080

800

---

---

Kunio Okimura et al

04

1069

---

---

---

K. Ramkumar et al

05

1072

820

447

---

Nur Selamoglu et al

06

1080

---

---

140

William J. Patric et al

07

1070

---

---

67.7

K. Ishii et al

08

1076.2

814.3

447.5

85.68

Present study

EDX of the deposited SiO2 films by PECVD

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Surface Morphology

Microphotograph of granular SiO2 film

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Surface Morphology

Microphotograph of uniform SiO2 film

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

EDAX of Deposited Silicon Nitride Films Element App Conc. NK 5.17 Si K 51.30 Cl K 1.27 Totals

Intensity Corrn. 0.1488 1.0817 0.6157

Weight% Weight% Sigma 34.78 1.70 47.42 0.82 2.06 0.30 84.26

Atomic% 58.70 39.92 1.37

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

FTIR Absorption Spectra of Deposited Si3N4 Films Si-H Stretch Si-N-Si Stretch Si-N Vibration 493.3 cm-1

N-H 1579.8 cm-1

Absorption

N-H Stretch 3378.8 cm-1

N-H bending 1179.9 cm-1

Wavenumber (cm-1 )

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

Total Hydrogen Concentration Vs. Substrate Temperature 7

H Concentration (X10

23

cm -3)

6

Si-H N-H H total

5 4 3 2 1 0 740

780

820

860

Deposition tem perature ( oC)

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

SEM of Deposited Silicon Nitride Films

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

CONCLUSIONS  The Department of Electronics has developed the capabilities to design various guided wave active and passives devices including laser diodes, optical power splitters, multi / demultiplexers etc  The infrastructure for the fabrication of the devices has been partly established and rest of the facilities would be established in near future

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA

D. K. Gautam, Department of Electronics, North Maharashtra University, Jalgaon-425 001 (MS) INDIA