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Department of Electrical & Computer Engineering Future Generation Solid-State Energy Conversion.

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Presentation on theme: "Department of Electrical & Computer Engineering Future Generation Solid-State Energy Conversion."— Presentation transcript:

1 Department of Electrical & Computer Engineering Future Generation Solid-State Energy Conversion Kyle Montgomery 1 May 12, 2014

2 About Me 2 To 2000In the beginning… 2004Bachelor’s Professional 2008Master’s 2012PhD PresentResearch & Lecturer Intern

3 Influences 3 Jerry Woodall Distinguished Professor, UC Davis NAE Member, National Medal of Technology Compound Semiconductor Materials & Devices David Wilt Tech Lead, Air Force Research Lab, Space Vehicles Former Lead PV Engineer at NASA Space Photovoltaics, III-V MOVPE Mark Lundstrom Distinguished Professor, Purdue NAE Member Electron Transport and Device Modeling

4 Overview 4 Motivation The Energy Dilemma Opportunities Research Photovoltaics Future Directions Teaching Experience: Purdue & UC Davis Future Directions

5 Overview 5 Motivation The Energy Dilemma Opportunities Research Photovoltaics Future Directions Teaching Experience: Purdue & UC Davis Future Directions

6 The Energy Dilemma (1/2) 1.We use too much energy 6 EIA, International Energy Outlook 2013 Total Global Energy Total Energy by Country OECD: Organization for Economic Cooperation and Development +60%

7 The Energy Dilemma (2/2) 2.We waste too much energy 7 Conversion Loss (62%) Coal (41%) Natural Gas (25%) Nuclear (21%) Renewables (12%) Residential (12%) Commercial (12%) Industrial (9%) Mostly Waste Heat US EIA, Monthly Energy Review (January 2014)

8 Opportunity: Solar Resource 8 Covering US ~20M TWh / yr 2011 US Electricity Consumption 4100 TWh Equiv. Land Area ~2000 km 2 ½ the size of Rhode Island

9 Wide Bandgap Cells for Multijunctions 9 K. Montgomery, PhD Thesis, 2012 E g > 2 eV

10 Opportunity: Lighting Efficiency 10 17% Percentage of total residential & commercial electricity used for lighting in US (EIA, 2011) Efficacy [lm / W] US DoE, Solid-State Lighting Technology Fact Sheet, PNNL-SA-94206, March Incandescent Halogen Compact Fluorescent Linear Fluorescent High Intensity Discharge (HID) Light Emitting Diode (LED)

11 Better Ways for Solid State Lighting 11 Current Technology: Low Cost, Decent Quality Ideal Technology: High Cost, Superior Quality NEED: True Green LED

12 Overview 12 Motivation The Energy Dilemma Opportunities Research Photovoltaics Future Directions Teaching Experience: Purdue & UC Davis Future Directions

13 Research Contributions Reviving Liquid Phase Epitaxy GaP Solar Cells –2x improvement in spectral response AlGaAs Solar Cells –Enhanced Luminescence Near Crossover –Towards Dual Junction Integration on Si III-V / II-VI Digital Alloys Integration to Novel Energy Conversion Systems 13

14 Semiconductor Menu 14

15 Liquid Phase Epitaxy – Rotating Chamber 15 K. Montgomery, PhD Thesis, 2012 Benefits: Perfected Crystal Structure Better Stoichiometry High Growth Rates Economical Challenges: Stable Growth Conditions Low Supersaturation

16 GaP Solar Cells 16 C. R. Allen, et al., Sol. Energ. Mat. Sol. C., 94, 865 (2010). Voltage (V) Wavelength (nm) Current Density (mA/cm 2 ) Internal QE

17 Gettering in GaP 17 K. Montgomery, et. al., JEM, 40, (2011). 975°C O-O- Liquid Solid Ga Al GaP Substrate AlGaP Mole Fraction Al Mole Fraction P P Mole Fraction Ga

18 Gettering Yields Higher Response 18 K. Montgomery, et. al., JEM, 40, (2011). Zn-O Zn-S Exciton

19 AlGaAs Solar Cells by LPE 19 X. Zhao et.al, PVSC 40 (2014), K. Montgomery, et. al., EMC (2012)

20 Non-Isovalent Alloys 20

21 ZnSe-GaAs Digital Alloy 21 Superlattice  Miniband formation Potential problem: intermediary compounds at interfaces S. Agarwal, K. H. Montgomery, et. al., Electrochemical and Solid-State Letters, 13, H5 (2010). Effective Band Gap

22 Wide Bandgap Cells for Hybrid PV-PT Goal: Maximize solar energy conversion using PV + Heat Benefit: Direct heat absorption allows for storage 22 K. Montgomery, et. al., PVSC 39 (2013) & Manuscript in Preparation System Efficiency Temperature (°C) PV Bandgap (eV)

23 Future Directions 23 Wide Bandgap Solar CellsEngineered Superstrates Non-Isovalent Semiconductors Gettered Devices Integrated Nanostructures Tandem Integration Hybrid Epitaxy III-V on Si Polycrystalline III-V ZnSe-GaAs Epitaxy Growth & Doping Heterojunction Devices

24 Overview 24 Motivation The Energy Dilemma Opportunities Research Photovoltaics Future Directions Teaching Experience: Purdue & UC Davis Future Directions

25 Teaching Experience: Purdue Teaching Assistant –2 semesters: Grad Level Microfabrication Lessons Learned –Textbook Knowledge ≠ Fab Skills –Laboratory Safety 25

26 Teaching Experience: UC Davis Lecturer –Undergrad Circuits Analysis –~200 students Lessons Learned (& still learning!) –Minimize loss in translation –Emphasize fundamentals, Expose details 26 kmontgomery.net/eng17 “…not only does he go on to teach us what we need to know to get by in circuits, he is a compelling lecturer, caring person, and above all he is able to deal with classroom issues with grace.”

27 Mentorship: UC Davis 27 PhD Students Undergraduates

28 Teaching Plans: Graduate Materials Science for Microsystems Engineering Microelectronics I Proposed Course 28 Solid-State Energy Conversion Materials & Devices REVIEW: Solid-State Physics, Material Properties, Thermodynamics Photovoltaics Light Emitting Diodes ThermoelectricsPiezoelectrics “Direct Energy Conversion” by Angrist (w/supplements) Emphasis on Recent Research

29 Teaching Plans: Undergraduate Circuits I-II (Adv.) Semiconductor Devices MATLAB Programming Clean and Renewable Energy Systems and Sources 29

30 Overview 30 Motivation The Energy Dilemma Opportunities Research Photovoltaics Future Directions Teaching Experience: Purdue & UC Davis Future Directions

31 Acknowledgements 31 Purdue University Prof. Mark Lundstrom, ECE Prof. David Janes, ECE Prof. Peide Ye, ECE Prof. Eric Kvam, MSE Prof. Peter Bermel, ECE Prof. Gerhard Klimeck, ECE Prof. Anant Ramdas, Physics Dionisis Berdebes, ECE Dr. Jayprakash Bhosale, Physics Yale University Prof. Minjoo Larry Lee, EE UC Davis Prof. Jerry Woodall, ECE Prof. Saif Islam, ECE Prof. Subhash Mahajan, CHMS Xin Zhao, ECE UCLA Dr. Paul Simmonds Air Force Research Laboratory David Wilt Dr. Alex Howard John Merrill

32 Department of Electrical & Computer Engineering Thank you! Any questions? 32

33 Department of Electrical & Computer Engineering Supplemental 33

34 ZnSe-GaAs Physical Alloy 34 Miscibility previously demonstrated N-type conductivity generally found Lack of prior work due to difficulty in suitable deposition technique W. M. Yim, JAP, 40, 2617–2623, 1969.

35 SiC Solar C ells suns R. P. Raffaelle et. al., 28 th PVSC, 2000, pp. 1257–1260.

36 AlGaAs Growth by LPE 36 K. Montgomery, et. al., EMC (2012)

37 InGaN Solar C ells 37 Full Spectrum Coverage Phase separation InGaN (37% In) Jampana, et al., Electron Devic. Lett., 31, 32 (2010). R. Singh and D. Doppalapudi, Appl. Phys. Lett., 70, 1089 (1997). Defects InGaN (16.8% In, 2.67 eV)

38 2.19 eV GaInP w/GaAsP Buffers on GaP 38 S. Tomasulo, et. al., PVSC 39, In 0.26 Ga 0.74 P

39 Wide Bandgap Cells for High-T 39 G. A. Landis, et. al., “High-Temperature Solar Cell Development,” NASA, Temperatures up to 450°C Bandgap Efficiency °C 900°C AM0 (FF = 0.80, P in = W/cm 2 )

40 Engineered Superstrates Superstrate: Substrate templated with a heterogeneous material III-V on Si –Needs thick buffer layers –Problem: Dislocation densities LPE may help (w/MOCVD) 40

41 41

42 Primary Photovoltaic Technologies 42 Low Cost, Low Efficiency η ~ 6-22% η ~ 28-39% (at xx suns) High Cost, High Efficiency First SolarSolFocus


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