ZnO PN Junctions for Highly-Efficient, Low-Cost Light Emitting Diodes

Prime Recipient: University of FloridaWork Performed Under Agreement: DE-FC26-04NT42271 U. S. Department of EnergyNational Energy Technology LaboratoryCOR: Ryan Egidi

Project ObjectivesDevelop solid state lighting technology based on wide bandgap ZnO light emitting diodes (LED)Achieve high p-type carrier concentrations in epitaxial (Zn,Mg)O thin filmsRealize band edge emission from a ZnO-based pn homojunctionAchieve band edge emission for ZnO-based pn heterojunctions that are designed to yield efficient light emission. Related objectivesUnderstand the doping behavior of phosphors and nitrogen in ZnO and ZnMgOIdentify the potential and limitations of ZnO pn junction LED performanceAchieve electroluminescence in polycrystalline ZnO-based pn junctions fabricated on glass.

Expected BenefitsEnhanced Performance in LEDsLight-emitting diode technologies are the most attractive approach to energy-efficient solid state lightingZnO appears equivalent to the nitrides ( leading material candidate) for all relevant optical properties and has an exciton state that is significantly more stable at room temperature holds significant potential to outperform the nitride devicesReduction in CostZnO-based devices have been realized using thin films deposited at temperatures on the order of 400-600C, which is significantly lower that that for the nitrides. Reduced temperature alone should lead to lower manufacturing costs. Functional ZnO electronic devices can be fabricated on inexpensive substrates, such as glass. For the large-area photonic application of solid state lighting, polycrystalline ZnO LEDs would present a remarkable opportunity for technology.

Budget PeriodProject Funding Profile Total costs 10/01/05-9/30/05$302,128Total costs 10/01/06-9/30/07$297,242

BP#1BP#2BP#3TotalGov. FundingCost ShareGov. FundingCost ShareGov. FundingCost ShareGov. FundingCost ShareRecipient$315,167$78,792$302,128$75,532$297,242$74,310$914,537$228,634CS %:20%20%20%20%

BP#3 Oct. 2006 Sept. 2007 (estimated)October24,000November24,000December24,000January24,000February24,000March24,000April24,000May24,000June24,000July24,000August27,000September30,242total297,242

BP#2 Oct. 2005 Oct. 2006 (estimated)October27,128November25,000December25,000January25,000February25,000March25,000April25,000May25,000June25,000July25,000August25,000September25,000total302,128

Project Status (Budget Period 2)ZnO-based pn junctions for light emitting diodesThree pertinent issues

Achieve high p-type carrier concentrations in epitaxial and polycrystalline films Materials issueRealizing band edge emission from pn homojunctionsProof of concept

Investigating pn heterojunction constructs that should yield efficient light emission.Device Development

Project Status (Budget Period 2)Research task with milestones in Budget Period 2

Reproducibility of p-type ZnO growthRTA annealing study400 800 Buffer : 20 mTorr for 1 hour Post-annealing for 1 hour (150mTorr) ZnO:P growth for 3 hours- StructureA) Temperature effects (Fixed pressure : 150mTorr)

B) Pressure effects (Fixed temperature 700 )Research task: Achieve 1017 cm-3 p-type carrier density in ZnO film

(ZnO:P0.005) - Hall data (150 mTorr growth pressure): p or n-type: p-type : n-type

GrowthTemp()As grownRTA temperature () / time (min)8509009502 min3 min2 min3 min1 min2 min3 min6004400 -cm3.9E+16cm-30.037cm2/Vs4400 -cm2.3E+15cm-30.63cm2/Vs140 -cm1.2E+17cm-30.37cm2/Vs9.0 -cm1.8E+18cm-30.38cm2/Vs1.1 -cm4.9E+18cm-31.2cm2/Vs0.76 -cm5.4E+18cm-31.5cm2/Vs6501700 -cm2.9E+15cm-31.3cm2/Vs490 -cm1.2E+16cm-31.0cm2/Vs70 -cm4.3E+17cm-30.20cm2/Vs5.0 -cm3.0E+18cm-30.41cm2/Vs6.3 -cm2.7E+18cm-3 0.36cm2/Vs11 -cm2.0E+19cm-30.028cm2/Vs700480 -cm1.4E+16cm-30.98cm2/Vs3400 -cm3.9E+15cm-30.47cm2/Vs1700 -cm8.8E+15cm-30.40cm2/Vs360 -cm4.2E+16cm-30.40cm2/Vs24-cm4.6E+17cm-30.56cm2/Vs17 -cm5E+17cm-30.71cm2/Vs19 -cm4.1E+17cm-30.80cm2/Vs39 -cm2.4E+17cm-30.66cm2/Vs7502.2 -cm4.8E+17cm-35.8cm2/Vs630 -cm1.4E+16cm-30.68cm2/Vs900 -cm1.0E+16cm-30.67cm2/Vs140 -cm2.2E+17cm-30.21cm2/Vs4.8 -cm1.1E+18cm-31.1cm2/Vs7.1 -cm4E+17cm-32.4cm2/Vs21 -cm9.5E+17cm-30.30cm2/Vs65 -cm1.0E+18cm-30.094cm2/Vs8002.0 -cm4.5E+17cm-37.1cm2/Vs360 -cm2.6E+16cm-30.66cm2/Vs1400 -cm5.1cm-30.91cm2/Vs100 -cm2.6E+16cm-32.4cm2/Vs4.9 -cm3.6E+18cm-30.36cm2/Vs17 -cm2E+18cm-3 0.15cm2/Vs4.5 -cm3.7E+18cm-30.38cm2/Vs15 -cm2.0E+17cm-32.2cm2/Vs

( ZnO:P0.005 ) Hall data (700C growth temperature): p or n-type: p-type : n-type

P(O2)(m Torr)As grownRTA temperature () / time (min)8509009502 min3 min1 min2 min3 min1 min2 min3 min150480 -cm1E+16cm-30.98cm2/Vs34004E+15cm-30.47cm2/Vs1700 -cm9E+15cm-30.40cm2/Vs360 -cm4E+16cm-30.40cm2/Vs24 -cm4E+17cm-30.56cm2/Vs17 -cm5E+17cm-30.71cm2/Vs19 -cm4E+17cm-30.90cm2/Vs39 -cm2E+17cm-30.68cm2/Vs1005.5 -cm2E+19cm-30.07cm2/Vs-9400-cm6E+13cm-310cm2/Vs20 -cm7E+17cm-30.44cm2/Vs76 -cm2E+17cm-30.39cm2/Vs34 -cm1E+18cm-30.14cm2/Vs33 -cm4E+16cm-35.3cm2/Vs38 -cm1E+18cm-30.11cm2/Vs36 -cm2E+18cm-30.08cm2/Vs501.1 -cm8E+18cm-30.65cm2/Vs8E+4-cm5E+13cm-31.6cm2/Vs4E+4-cm4E+13cm-34.3cm2/Vs170 -cm1E+16cm-33.4cm2/Vs280 -cm9E+16cm-30.24cm2/Vs4.7E6-cm1E+12cm-31.1cm2/Vs33 -cm2E+17cm-30.94cm2/Vs8.4 -cm4E+18cm-30.20cm2/Vs28 -cm4E+19cm-30.005cm2/Vs101.4 -cm4E+18cm-31.3cm2/Vs9400 -cm4E+16cm-30.02cm2/Vs3100 -cm5E+15cm-30.44cm2/Vs27 -cm9E+16cm-32.6cm2/Vs5700 -cm4E+16cm-30.03cm2/Vs51 -cm9E+18cm-30.01cm2/Vs45 -cm6E+16cm-32.5cm2/Vs25 -cm1E+19cm-30.02cm2/Vs58 -cm3E+18cm-30.04cm2/Vs10.75 -cm9E+18cm-30.90cm2/Vs1000-cm2E+17cm-30.03cm2/Vs840 -cm4E+17cm-30.02cm2/Vs3.3 -cm3E+18cm-30.61cm2/Vs7.6 -cm3E+18cm-30.28cm2/Vs220 -cm9E+16cm-30.33cm2/Vs2.3 -cm3E+18cm-30.89cm2/Vs2.9 -cm5E+18cm-30.43cm2/Vs4.6 -cm4E+18cm-30.33cm2/Vs

2. Zn0.95Mg0.05O:P0.02 (Hall data)p=1016cm-3

GrowthTemperature()As grownRTA temperature ()600700800900550(ZMP-13)4.98E+16(M) 0.14546(R) 860.872.70E+17(M) 0.085742(R) 269.233.67E+16(M) 0.25074(R) 678.835.20E+14(M) 1.2396(R) 9591.41.03E+17(M) 0.14526(R) 419.61600(ZMP-14)7.18E+16(M) 1.4197(R) 61.3091.54E+17(M) 0.37251(R) 108.867.06E+16(M) 0.37137(R) 238.781.59E+16(M) 0.40281(R) 962.382.89E+17(M) 0.58556(R) 36.798650(ZMP-15)4.92E+13(M) 0.12126(R) 1.09E+69.34E+17(M) 0.5125(R) 129034.50E+13(M) 2.3158(R) 605009.44E+13(M) 0.82754(R) 781266.16E+17(M) 0.52519(R) 19.321650(ZMP-16)3.49E+18(M) 34.55(R) 0.0517143.90E+18(M) 34.913(R) 0.0458423.45E+18(M) 33.670(R) 0.0537342.53E+17(M) 3.0596(R) 8.06101.38E+17(M) 5.33(R) 8.47

1. Zn0.9Mg0.1O:P0.02 (Hall)p=1-6x1015 cm-3

RTA temperatureAs grown600700800850900925975Thickness of buffer layer(nm)< 500 >30( ZMP-1 )3.6735E14(M) 0.5361(R) 324572.5582E+150.71513394.21.6799E+160.40346925.056.3720E+140.6093116061100( ZMP-2 )2.6561E14(M) 0.4735(R)496552.1134E+150.25347116522.8783E+150.341036357.14.1998E+140.2648057642200( ZMP-3 )2.8614E15(M) 0.1893(R) 115162.7098E+140.45735505651.0210E+140.5057912131Semi-insulating4.27E+14(M) 18.25(R) 788400( ZMP-4 )7.4256E17(M) 4.5337(R) 1.8551.0167E+150.935406551.32.9490e+141.012920883Semi-insulating1.29E+170.0549875.03GrowthTemperature< 200 nm >550 ( ZMP-10 )6.8235E+15(M) 1.2349(R) 732.494.56E+16(M) 0.11955(R) 1140.17.72E+16(M) 0.1129(R) 720.156.36E+16(M) 2.6358(R) 37.156.31E+17(M) 7.9413(R) 1.2466600 ( ZMP-5 )7.784E+17(M) 0.1382(R) 57.3881.7995E+150.420288214.43.5071E+140.4924436207Semi-insulatingSemi-insulating(875 )600 ( ZMP-11 )1.1999E+13(M) 56.677(R) 8932.85.58E+15(M) 0.12621(R) 8909.48.24E+14(M) 0.21207(R) 357161.0427E+12(M) 139.02(R) 464524.35E+17(M) 1.4595(R) 9.8393650 ( ZMP-12 )4.2397E+16(M) 0.39604(R) 371.646.95E+16(M) 0.07554(R) 1198.41.64E+17(M) 0.058(R) 6571.68E+16(M) 0.24019(R) 1564.74.28E+17(M) 1.9607(R) 7.4443700 (ZMP-6)1.499E+17(M) 1.1119(R) 37.4217.115E+160.411212.464.21E+160.2797531.031.095E+151.11355094.76.4643E+160.52519183.36800 (ZMP-7)4.67E+18(M) 39.436(R) 0.0338753.36E+1840.780.04553.44E+1511.748156.652.824E+14100.66218.986.7577E+161.367667.410900 (ZMP-8)1.368E+19(M) 33.410(R) 0.0136551.4026E+1927.5670.0161441.4829E+192.31440.182087.0575E+170.906329.76473.8507E+171.84398.7689

Narrow Omega Rocking Curve Hall datan = 2.4E+16 ( /cm3 ) = 87.7 ( cm2/Vs ) = 3.1 ( ohmcm )High-quality undoped ZnO epitaxial films realized by PLD( rms : 1.557 nm)

p-n homojunctions in n-ZnO bulk single crystals by diffusion from a Zn3P2 sourcep-n junctions have been formed in lightly n-type (1017 cm-3) bulk, single-crystal ZnO substrates by diffusion of P from a Zn3P2 dopant source in a closed-ampoule system. Research task: Determine efficacy of pn homojunction for LED

Electroluminescence From N+-Implanted Bulk ZnOBand-Edge Electroluminescence From N+-Implanted Bulk ZnOStudies of phosphorus and nitrogen doping via ion implantation carried out. Rectifying junctions and light emission realized. N+ ion implantation at moderate doses (1012-1013 cm-2) into nominally undoped (n~1017 cm-3) bulk single-crystal ZnO substrates followed by annealing in the range 600-950C was used to fabricate diodes that show band-edge electroluminescence at 120K (~390 nm) under forward bias conditions.

Research task: Achieve UV light emission from pn homojunction device

N-implanted ZnO crystals:Light Intensity Performance Onset > 8 volts

Devices600C RTA800C RTA950C RTAP at 100mA (Lumen)3.5710-98.510-100

Si diode testLight emission for diodes with onset>5 volts

Attribute optical emission to high-field carrier injectionCurrent focus is on pn junction heterostructure devices for minority carrier injection LEDEpitaxial ZnMgO doped with P or NHigh hole concentrationFormation of heterojunction deviceMinority carrier injection

Vertical ZnO NWs/PEDOT LED Nanowire ArrayThe cross section schematic of ZnO nanowires LED

Efforts toward epitaxial light-emitting homojunction and/or heterojuctionMultiple devices fabricated and testedZnO:P/ZnO:Ga/ZnO buffer/Al2O3ZnO:P/ZnO:Ga/ZnO buffer/ZnO single crystalZnMgO:P/ZnO:Ga/ZnO buffer/Al2O3ZnO:As/ZnO:Ga/ZnObuffer/Al2O3High leakage currents (non-rectifying I-V) observed as persistent limitationPossible origins of leakage currentsLeakage paths along ZnO surface due to processing-induced surface conductionP-type to n-type conversion of P-doped ZnO due to processingPinholes in p-type layer due to surface roughnessEfforts in Budget Period 3 will focus on identifying and eliminating cause(s) of leakage currents

3. ZnO:P0.01 ( PL of p-type samples ) ZP-4(950) (Tg = 600) ZP-6(900) (Tg = 700) ZP-6(950) (Tg = 700) ZP-7(900) (Tg = 800)Band edge PL and p-type seen in P-doped ZnO!

/ cm3Ohm-cmCm2/v-sRTA1.61E+1777.670.4998950

/ cm3Ohm-cmCm2/v-sRTA1.55E+1748.8270.8139900

/ cm3Ohm-cmCm2/v-sRTA2.37E+15801.363.2161950

/ cm3Ohm-cmCm2/v-sRTA1.98E+1746.570.67867900

Zn0.9Mg0.1O:P0.02 ( PL of p-type samples ) ZMP-3 (Tg = 500) ZMP-5 (Tg = 600) : Not reproducible ZMP-10 (Tg = 550) ZMP-3(700) (Tg = 500) ZMP-6(800) (Tg = 700) No evidence for band edge PL in ZnMgO:P films

/ cm3Ohm-cmCm2/v-sRTA2.86E+15115160.1893as grown

/ cm3Ohm-cmCm2/v-sRTA6.82E+15732.491.2349as grown

/ cm3Ohm-cmCm2/v-sRTA7.78E+1757.3880.1382as grown

/ cm3Ohm-cmCm2/v-sRTA1.02E+14121340.50579700

/ cm3Ohm-cmCm2/v-sRTA1.10E+155094.71.1135800

Good PL(small deep level) + low carrier density< PL >< XRD rocking curve > : FWHM = 0.229 < Hall > : 1.07E+17 /cm3 , 36.44 cm2/v-s , 1.65 ohm-cm Growth condition :

- Substrate : sapphire c-plane - Target : undoped ZnO - Laser : 350 mJ / 1Hz - Working pressure (O2 + O3 ) : 30 mTorr - Ablation time : 2 hr - Growth temperature : 800Candidate i layer for p-i-n LED

The lowest carrier density ( Still working ) not completed< Hall > : 1.99+16 /cm3 , 22.30 cm2/v-s , 15.75 ohm-cm< PL > Growth condition :

- Substrate : sapphire c-plane - Target : undoped ZnO - Laser : 350 mJ / 1Hz - Working pressure (O2 + O3 ) : 30 mTorr - Ablation time : 2 hr - Growth temperature : 800 ( buffer layer : MgO at 450 , P : 10-4, time : 1 hr , 350 mJ/ 1Hz )< structure >( At many other conditions, the carrier density also shows low 16 )MgO buffer: lowers background carrier density by factor of 5

2. Epi-layer - Laser : 350 mJ / 1Hz - Pressure (O2 + O3 ) : 30 mTorr - Temperature : 800 - Ablation time : 2 hr1. Growth condition500 800 1. Buffer layer - Laser : 350 mJ / 1Hz - Pressure (O2 + O3 ) : 30 mTorr - Temperature : 500 - Ablation time : 2 hr 50 nm 100 nm 200 nm 300 nmBufferEpi-layerConditions for next slide

3. HallLow temp growth of ZnO buffer yields low mobility in undoped ZnO films

Thickness of buffer layer(nm)Concentration(/cm3)Mobility(cm2/vs)Resistivity(ohmcm)504.35E+161.1130.701005.12E+160.523233.642002.88E+160.08242642.53002.16E+170.0414700.24As grown1.07E+1736.441.65MgO (~50nm)1.99E+1622.3015.75

Growth conditionsSapphire SubstrateBuffer layer (25nm)Undoped ZnO( ~ 1um) Bulk layer growth- Target : undoped ZnO- Tg : 850 - Pressure : 10 mTorr ( O2 + O3 mixture gas ) Laser : 180 mJ / 4 Hz Ablation time : 2 hrs 2 min ( 1.22 / s )

Buffer layer growth Target : undoped ZnO- Tg : 850 Pressure ( O2 + O3 mixture gas ) without buffer 0.01 mTorr 0.1 mTorr 1 mTorr 10 mTorr - Laser : 180 mJ / 1 Hz Ablation time : 9 min ( 0.53 / s ) Characterization

XRD rocking curve AFM SEM Optical microscopic Hall ThicknessConditions for next slide

Hall Resistivity Carrier density MobilityExcellent mobility for ZnO films!!!

Working pressure of buffer layer(mTorr)Concentration(/cm3)Mobility(cm2/vs)Resistivity(ohmcm)Without buffer1.6495E1873.610.051460.012.7502E1885.4760.026610.12.3765E1887.6060.0300112.2949E1885.4430.03187101.8874E1887.3710.03803

FWHM of XRD rocking curveLow temperature nucleation yields poorer crystallinity

Growth temperature of the buffer layer ()Omega rockingFWHM (arcsec)450 242.64(0.0674)550 210.96(0.0586)650 206.64(0.0574)750 49.32(0.0137)850 47.16(0.0131)

Hall Resistivity Carrier density MobilityLow temperature nucleation yields low mobility

Growth temperature of buffer layer ()Concentration(/cm3)Mobility(cm2/vs)Resistivity(ohmcm)4501.9011E+1865.6720.0501275507.4896E+1783.3490.100356501.7959E+1873.5080.04373817508.5180E+1778.1110.0841278502.2949E1885.4430.03187

Optimized thick undoped ZnO films Growth conditionsSapphire SubstrateBuffer layer (25nm)Undoped ZnO( ~ 1um) Bulk layer growth- Target : undoped ZnO Tg : 650 - Pressure : 10 mTorr ( O2 + O3 mixture gas ) Laser : 180 mJ / 4 Hz Ablation time : 2 hrs 20 min ( 1.22 / s )

Buffer layer growth Target : undoped ZnO- Pressure : 1m Torr ( O2 + O3 mixture gas ) Tg : 850 - Laser : 180 mJ / 1 Hz Ablation time : 9 min ( 0.53 / s )Conditions for next 2 slides

AFM 10 by 10 5 by 5 ( rms : 3.323 nm)( rms : 1.557 nm)50 nm30 nm

Omega Rocking Curve Hall data

: 2.3971E+16 ( /cm3 ) ,87.68 ( cm2/vs ) , 3.1217 ( ohmcm )

N-type ZnO films ( Ga v.s. Al ) Growth condition Surface morphology - OM - AFM Crystallinity - XRD rocking curve (FWHM) Electrical properties - Hall measurement

Growth conditions n-type Bulk layer growthTarget : ZnO : Al (0.01 at %) ZnO : Ga (0.01 at %)

- Tg : 650 - Pressure : 10 mTorr ( O2 + O3 mixture gas ) Laser : 180 mJ / 4 Hz Ablation time : 2 hrs 20 min ( 1.22 / s )

ZnO Buffer layer growth Target : undoped ZnO- Pressure : 1m Torr ( O2 + O3 mixture gas ) Tg : 850 Laser : 180 mJ / 1 Hz Ablation time : 9 min ( 0.53 / s )

AFM ZnO:Al ZnO:Ga Roughness rms : 14.174 nm )( Roughness rms : 4.546 nm )100 nm50 nm

Roughness rms ( 10 X 10 ) FWHM of XRD rocking curve Hall

Roughness rms (nm)ZnO:Al14.174ZnO:Ga4.546

Concentration(/cm3)Mobility(cm2/vs)Resistivity(ohmcm)ZnO:Al1.4050E+1927.3630.016231ZnO:Ga6.8788E+1820.9270.043497

Omega rocking curve - FWHM (arcsec)ZnO:Al700 (0.1945)ZnO:Ga513 (0.1425)

1. SEM images ( ZLP-19, Tg = 700, 50mTorr ) + Tube furnace annealing (700 , 1hr) ( ZnO:P / ZnO:Ga / ZnO thin buffer / Sapphire c-plane)Evidence for particle growth upon annealing of Ga-doped ZnO?

pn junction formation and properties

IV for ZnMgO:P/ZnO junctionsRectifying junctions with 3-4 V turn-on

After annealingConductivity of N-type 500nm ZnMgO:P/200nm undoped ZnO buffer layer/sapphireRectifying turn-on at 3-4 volts

Annealing temperature600oC700oC800oC700oCZnMgO:PIncrease(current: 8*10-10 to 3*10-9 at 5V)Decrease(current: 1*10-8 to 3*10-9 at 5V)Decrease(current: 1.5*10-8 to 4*10-9 at 5V)800oCZnMgO:PIncrease(current: 4*10-9to 1.7*10-7 at 5V)Increase(current: 6*10-12 to 7*10-8 at 5V)Increase(current: 4*10-12 to 6*10-8 at 5V)900oCZnMgO:PIncrease(current: 5*10-12to 3*10-8 at 5V)Increase(current: 3.5*10-12to 2.5*10-10 at 5V)Increase(current: 6*10-12to 2.8*10-10 at 5V)

Annealing ZnMgO:P/ZnO/Al2O3 junctionsAfter annealing

conductivity600oC700oC800oC30 nm ZnOincreaseincrease(current: 10-8 to 10-7 at -5V)increase100 nm ZnOdecreaseincrease(current: 1.5*10-8 to 4*10-8 at -5V)decrease200 nm ZnOdecreasedecreasedecrease(current: 10-8 to 10-9 at -5V)400 nm ZnOdecreasedecreasedecrease(current: 10-5 to 10-9 at -5V)600C ZnMgO:Pdecreasedecreasedecrease(current: 10-6 to 10-9 at -5V)

CuCrO2: possible alternative p-type oxide for hole injectionEpitaxial film growth achievedMg doping reported to produce p-type conductivityResearch task: Investigate alternative p-type oxides as hole injection materials

Research task: Investigate alternative p-type oxides as hole injection materialsGa-doped SnO2Hall measurements:P-typeHole concentration 2x1019cm-3(possible IP)

Changes to baseline plan in Budget Period 2Experimental emphasis on epitaxial films on sapphireExplored alternative p-type oxides as hole injectorsExplored light emission from implanted ZnO and nanowires

Relationship of Budget Period 2 Tasks to Project Success

Status of project milestones in Budget Period 2

Status of project milestones in Budget Period 3

Status of project milestones in Budget Period 3 (continued)

Justification for continuation of projectProgress made towards all milestones for Budget Period 2Achieved p-type ZnO with p = mid-1017/cm3Light emission observed from implanted junctionsHomo- and heterojunction device fabrication process establishedEpitaxy of alternative p-type hole injection material identifiedOriginal justification for project (promise of ZnO for light emitting diodes) remains validReports in Applied Physics Letters of light emission in As-doped ZnBeO LED

Onset of non-linear IV at 10 V, not 3.2 VEL seen with current > 10 mA

p-n LED Using Sputtering [Jae-Hong Lim et al.]Advance Material, 2006.ZnO LED Results for Other GroupsWell-defined IV onset at ~ 3.2 V

Year 1Year 2Year 3Overview of remaining Budget Periods

Year 1Year 2Year 3

DELIVERABLESThe recipient will provide periodic, topical and final reports in accordance with the Federal Assistance reporting Checklist provided with the program solicitation. The recipient will provide monthly e-mail correspondence with the program manager that will indicate task and subtask updates, expanded summary of project results, key milestones and significant accomplishments, presentations and publications, site visit and travel descriptions. The recipient will also provide briefings for presentation upon request. The recipient will present a technical paper at the DOE/NETL Annual Contractors Review Meeting.

Final product/commercializationObjective of project is to realized viable LED technology based on ZnO pn heterojunctionCommercialization would be through a yet to be determined industrial partner

This is another remarkable p-n LED achieved by Dr. Parks group using sputtering technique. They use phosphorus as accepter for p-type ZnO. The turn-on voltage is 3.2 V with EL emission peak at 380nm.