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Six periods of 2-nm-thick In0.15Ga0.85N/13-nm-thick GaN blue emitting multi-quantum-well (MQW) layers are grown on sapphire (Al2O3) and silicon (Si) substrates. X-ray diffraction, Raman spectroscopy, atomic force microscopy, temperature-dependent photoluminescence (PL), Micro-PL, and time-resolved PL are used to compare the structural and optical properties, and the carrier dynamics of the blue emitting active layers grown on Al2O3 and Si substrates. Indium clustering in the MQW layers is observed to be more pronounced on Al2O3 than those on Si as revealed through investigating band-filling effects of emission centers, S-shaped peak emission energy shifts with increasing temperature, and PL intensity-peak energy spatial nonuniformity correlations. The smaller indium clustering effects in MQW on Si are attributed to the residual tensile strain in the GaN buffer layer, which decreases the compressive strain and thus the piezoelectric polarization field in the InGaN quantum wells. Despite a 30% thinner total epitaxial thickness of 3.3 µm, MQW on Si exhibits a higher IQE than those on Al2O3 in terms of internal quantum efficiency (IQE) at temperatures below 250 K, and a similar IQE at 300 K (30% vs 33%). These results show that growth of blue emitting MQW layers on Si is a promising approach compared to those conventionally grown on Al2O3.
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Dependence of carrier escape lifetimes on quantum barrier thickness in InGaN/GaN multiple quantum well photodetectors
We reported significant improvements in device speed by reducing the quantum barrier (QB) thicknesses in the InGaN/GaN multiple quantum well (MQW) photodetectors (PDs). A 3-dB bandwidth of 700 MHz was achieved with a reverse bias of -6 V. Carrier escape lifetimes due to carrier trapping in the quantum wells (QWs) were obtained from both simulation and experimental fitting, identifying carrier trapping as the major speed limiting factor in the InGaN/GaN MQW PDs.
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- Award ID(s):
- 1725797
- PAR ID:
- 10175856
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Express
- Volume:
- 28
- Issue:
- 16
- ISSN:
- 1094-4087; OPEXFF
- Format(s):
- Medium: X Size: Article No. 23796
- Size(s):
- Article No. 23796
- Sponsoring Org:
- National Science Foundation
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