Luminescence and ultrafast phenomena in InGaN multiple quantum wells

Viswanath, Annamraju Kasi; Lee, J.I.; Kim, S.T.; Yang, Gye Mo; Lee, H.J.; Kim, Dongho

doi:10.1016/j.tsf.2006.07.110

Cited by 3 publications

(2 citation statements)

References 36 publications

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“…The differences were interpreted in terms of exciton trapping by the local potential minima due to the compositional inhomogeneities. Similar results were reported by Viswanath et al [118]. They interpreted the large PL linewidth to inhomogeneous broadening from compositional fluctuations due to spinodal decomposition.…”

Section: Led Performancesupporting

confidence: 90%

Microstructures produced during the epitaxial growth of InGaN alloys

Stringfellow¹

2010

Journal of Crystal Growth

159

123

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Section: Led Performancesupporting

confidence: 90%

Microstructures produced during the epitaxial growth of InGaN alloys

Stringfellow¹

2010

Journal of Crystal Growth

159

123

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“…These lead to generations of considerable amounts of nitrogen vacancies, pits, In-rich clusters and/or structure defects in the film to deteriorate its material properties. [8][9][10][11][12][13][14][15][16][17] In our previous work, we have employed a so-called the two-heater MOVPE horizontal reactor, consisting of a pair of paralleled ceiling and substrate heaters, 18 to grow InGaN films. We demonstrated its ability in preparing high In-content thick InGaN films with emission wavelength extended into infrared color region, and more importantly exhibiting good optical-quality and high spectral uniformity.…”

mentioning

confidence: 99%

Incorporation Behaviors of In and Ga in the Two-Heater MOVPE Growth of InGaN Films

Cheng

Lee

et al. 2016

ECS J. Solid State Sci. Technol.

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Incorporation behaviors of In and Ga of InGaN films grown by the two-heater metal-organic vapor-phase epitaxial horizontal reactor is investigated by varying growth parameters, such as the substrate temperature, ceiling temperature and reactor pressure. Two In loss mechanisms are observed by the analysis of the concentration and temperature profiles in the deposition zone. The gas-phase parasitic-loss mechanism (activation energy ∼ 34.2 ± 0.1 kcal/mol) is significant in the ceiling temperature T ceil ≥ 800 • C and at substrate temperature (T sub ) of 600 • C. The decomposition-loss mechanism, which arises from In desorption on the growing surface, is significant in T sub > 625 • C region. The desorption activation energy obtained is 28.0 ± 0.1 kcal/mol, which is close to that of . This suggests the In decomposition-loss mechanism in InGaN growth does not differ substantially from that in binary InN growth. On the other hand, the gas-phase parasitic-loss mechanism of Ga is negligible in the growth condition that we have explored. Exception is found for reactor pressure at T ceil = 950 • C, where both factors advantageous and disadvantageous to Ga incorporation are unambiguously observed. We have proposed explanation for the above observation. The promising electronic and optical properties of InGaN alloy, such as high two-dimensional electron gas (2DEG) electron mobility, wide tunability of photon emission energy from 0.7 to 3.4 eV, have given rise to numbers of applications in the past decade. These include high power and high electron mobility transistor (HEMT), visible light emitting devices, tandem solar cell, and solid state lighting.1-7 To realize, a method that capable of growing device-quality III-V nitrides is essential. Among all growth methods, metal-organic vapor-phase epitaxy (MOVPE) has proved itself to be the most reliable and major tool to produce these devices with mass-production feasibility. However, difficulties arise for this method in preparing high In content In x Ga 1−x N film (x > 30%) with acceptable optical and electrical properties. This stems mainly from the intrinsic properties of material itself, such as thermal instability of InN, wide miscibility gap, and large thermal-and lattice-mismatch between InGaN layer and underlying GaN base layer, and poor cracking efficiency of NH 3 . These lead to generations of considerable amounts of nitrogen vacancies, pits, In-rich clusters and/or structure defects in the film to deteriorate its material properties. [8][9][10][11][12][13][14][15][16][17] In our previous work, we have employed a so-called the two-heater MOVPE horizontal reactor, consisting of a pair of paralleled ceiling and substrate heaters, 18 to grow InGaN films. We demonstrated its ability in preparing high In-content thick InGaN films with emission wavelength extended into infrared color region, and more importantly exhibiting good optical-quality and high spectral uniformity. For instance, a sample with x = 0.40 In x Ga 1−x N film has a mean emission wavelength of 808 ± 6 nm a...

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Thermal droop in III-nitride based light-emitting diodes: Physical origin and perspectives

Meneghini

Santi

Tibaldi

et al. 2020

Journal of Applied Physics

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This tutorial paper focuses on the physical origin of thermal droop, i.e., the decrease in the luminescence of light-emitting diodes (LEDs) induced by increasing temperature. III-nitride-based LEDs are becoming a pervasive technology, covering several fields from lighting to displays, from automotive to portable electronics, and from horticulture to sensing. In all these environments, high efficiency is a fundamental requirement, for reducing power consumption and system cost. Over the last decade, a great deal of effort has been put in the analysis of the efficiency droop, the decrease in LED internal quantum efficiency (IQE) induced by high current density. On the other hand, an IQE decrease is observed also for increasing temperature, a phenomenon usually referred to as thermal droop. For commercial LEDs, the IQE decrease related to thermal droop can be comparable to that of efficiency droop: for this reason, understanding thermal droop is a fundamental step for making LEDs capable of operating at high temperature levels. In several fields (including street lighting, automotive, photochemical treatments, projection, entertainment lighting, etc.), compact and high-flux light sources are required: typically, to reduce the size, weight, and cost of the systems, LEDs are mounted in compact arrays, and heat sinks are reduced to a minimum. As a consequence, LEDs can easily reach junction temperatures above 85–100 °C and are rated for junction temperatures up to 150–175 °C (figures from commercially available LED datasheets: Cree XHP70, Osram LUW HWQP, Nichia NVSL219CT, Samsung LH351B, and LedEngin LZP-00CW0R) and this motivates a careful analysis of thermal droop. This paper discusses the possible physical causes of thermal droop. After an introduction on the loss mechanisms in junctions, we will individually focus on the following processes: (i) Shockley–Read–Hall (SRH) recombination and properties of the related defects; (ii) Auger recombination and its temperature dependence, including the discussion of trap-assisted Auger recombination; (iii) impact of carrier transport on the thermal droop, including a discussion on carrier delocalization, escape, and freeze out; (iv) non-SRH defect-related droop mechanisms. In addition, (v) we discuss the processes that contribute to light emission at extremely low current levels and (vi) the thermal droop in deep ultraviolet LEDs, also with reference to the main parasitic emission bands. The results presented within this paper give a tutorial perspective on thermal droop; in addition, they suggest a pathway for the mitigation of this process and for the development of LEDs with stable optical output over a broad temperature range.

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Luminescence and ultrafast phenomena in InGaN multiple quantum wells

Cited by 3 publications

References 36 publications

Microstructures produced during the epitaxial growth of InGaN alloys

Microstructures produced during the epitaxial growth of InGaN alloys

Incorporation Behaviors of In and Ga in the Two-Heater MOVPE Growth of InGaN Films

Thermal droop in III-nitride based light-emitting diodes: Physical origin and perspectives

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