研究目的
To elucidate how di?erent growth mode and composition of barriers can in?uence the QW properties and their PL and to ?nd optimal QW capping process, to suppress the In desorption from QWs and to maintain the QW PL e?ciency.
研究成果
The best PL results and hence optimal upper interface technology was achieved when the growth after QW formation was not interrupted, but immediately continued during the temperature ramp by the growth of (In)GaN capping layer with small introduction of TMIn into the reactor. Optimal barrier between QW with respect to PL results was found to be pure GaN. The InGaN desorption was considerably suppressed and three times higher In concentration and two times thicker QWs were achieved for the same QW growth parameters without deterioration of PL results.
研究不足
The study is limited to the specific conditions of MOVPE growth and the particular materials used (InGaN/GaN). The findings may not be directly applicable to other material systems or growth methods.
1:Experimental Design and Method Selection:
The study focuses on the technology procedure for growth of upper quantum well (QW) interfaces in InGaN/GaN QW structure when di?erent temperature for QW and barrier epitaxy is used.
2:Sample Selection and Data Sources:
Samples were prepared on Aixtron 3 × 2 CCS MOVPE System equipped by Laytec EpiCurveTT apparatus for in situ measurement of re?ectivity and curvature.
3:List of Experimental Equipment and Materials:
Trimethylgallium (TMGa) and ammonia (NH3) were used as precursors with a hydrogen carrier gas for the growth of bu?er layers, triethylgallium (TEGa), trimethylindium (TMIn), ammonia with nitrogen carrier gas were used for the growth of MQW region including barriers.
4:Experimental Procedures and Operational Workflow:
Structures were prepared on bu?er layers with optimized technology with respect to PL properties. The upper 1000 nm of the bu?er layer was grown at 150 mbar reactor pressure and was n-type doped using SiH
5:The whole MQW active region was grown at reactor pressure 400 mbar and NH3 ?ow rate of 6 l/min. Data Analysis Methods:
Photoluminescence was used as the main method for the evaluation of the structure quality. A semiconductor laser LD-375 emitting at 375 nm was used for the photoluminescence excitation. The luminescence signal was detected by a GaAs photo-multiplier tube.
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Laytec EpiCurveTT
EpiCurveTT
Laytec
Used for in situ measurement of re?ectivity and curvature.
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200 kV JEOL JEM 2011 microscope
JEM 2011
JEOL
Used for cross sectional TEM (XTEM) and high resolution TEM (HRTEM) observations.
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Aixtron 3 × 2 CCS MOVPE System
3 × 2 CCS
Aixtron
Used for the preparation of samples.
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Semiconductor laser LD-375
LD-375
Used for the photoluminescence excitation.
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GaAs photo-multiplier tube
Used for detecting the luminescence signal.
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Double monochromator SDL-1
SDL-1
Used for detecting the resulting photoluminescence.
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Lock-in ampli?er
Used for synchronous detection technique.
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EQ99X laser driven light source
EQ99X
Used for photoluminescence excitation-emission maps measurement.
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Jobin Yvon Gemini 180 monochromator
Gemini 180
Jobin Yvon
Used for filtering the light source.
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Newport 918D Low power calibrated photodiode sensor
918D
Newport
Used for calibrating the apparatus.
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Jobin-Yvon TRIAX320 monochromator
TRIAX320
Jobin-Yvon
Used for detecting the emitted light from the sample.
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Cooled CCD detector
Used for detecting the emitted light from the sample.
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