High speed, low driving voltage vertical cavity germanium-silicon modulators for optical

 
 
 
ix 
Chapter 3
 
SiGe Material Growth ............................................................................. 34
 
3.1
 
SiGe Alloy Surface Morphology ................................................................ 34
 
3.2
 
Growth Techniques ..................................................................................... 37
 
3.2.1
 
Deposition Systems .......................................................................... 37
 
3.2.2
 
3-D growth Suppression ................................................................... 38
 
3.2.3
 
Profile Control .................................................................................. 39
 
3.3
 
Chemical Vapor Deposition (CVD) Approach ........................................... 40
 
3.3.1
 
System Introduction .......................................................................... 40
 
3.3.2
 
Growth Calibrations ......................................................................... 42
 
3.3.3
 
Growth Rate Design ......................................................................... 43
 
3.3.4
 
SiGe Growth Model ......................................................................... 46
 
3.3.5
 
Doping Control ................................................................................. 48
 
3.4
 
SiGe Buffer Layer Growth .......................................................................... 49
 
3.4.1
 
Multiple SiGe Buffer Growth Approach .......................................... 49
 
3.4.2
 
Direct Buffer Growth........................................................................ 52
 
3.5
 
Ge/SiGe Quantum Well Structure Growth ................................................. 54
 
3.5.1
 
Stain Balanced Structure .................................................................. 54
 
3.5.2
 
Growth Techniques .......................................................................... 55
 
3.6
 
Selective Growth ......................................................................................... 56
 
Chapter 4
 
Device Fabrication ................................................................................... 60
 
4.1
 
DC PIN Diode Fabrication .......................................................................... 60
 
4.2
 
Modulator DC Operation ............................................................................ 61
 
4.3
 
AC High-speed Modulator Fabrication....................................................... 64
 
4.4
 
Summary ..................................................................................................... 67
 
Chapter 5
 
High Speed Characterization ................................................................... 68
 
5.1
 
High Speed E-O Response .......................................................................... 68
 
5.1.1
 
Measurement Setup .......................................................................... 68
 
5.1.2
 
Large Signal Measurements ............................................................. 69
 
5.1.3
 
Small Signal Measurements ............................................................. 70
 
5.2
 
Pump Probe Measurement .......................................................................... 76
 
5.2.1
 
Method .............................................................................................. 77
 
5.2.2
 
Experimental Setup .......................................................................... 78
 
5.2.3
 
Measurement Result ......................................................................... 80
 
5.2.4
 
Summary ........................................................................................... 82
 
Chapter 6
 
Conclusions ............................................................................................. 83
 
6.1
 
Summary ..................................................................................................... 83
 
6.2
 
Future Work ................................................................................................ 84
 
6.2.1
 
Material Growth Improvements ....................................................... 85
 
6.2.2
 
Cavity Modulator .............................................................................. 85
 
6.2.3
 
Waveguide Device ............................................................................ 86
 
6.2.4
 
Group IV Laser Integration .............................................................. 86
 
Appendix A .................................................................................................................. 88
 
Appendix B ................................................................................................................... 90
 
Bibliography ................................................................................................................. 92
 

---

 
 
 
x