Influence of temperature on different optoelectronic characteristics of InGaN light emitting diodes

Dalapati, Pradip; Manik, Nabin Baran; Basu, A. N.

doi:10.1007/s11082-017-1104-6

Cited by 6 publications

(2 citation statements)

References 56 publications

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“…Figure f shows the time decay constant map resulting from fitting an exponential decay to the data observed after turning off the laser in each pixel. The decay, of the order of tens of seconds, is extremely long if we compare it with the reported carrier lifetimes for GaN, of the order of ns. − However, the measured decay time is on the order of some traps’ emission rate, such as a hole trap associated with carbon-related defects . Analogously, very slow restoration of the dark band bending reported by Sabuktagin et al was attributed to charging and discharging of the surface states.…”

Section: Resultsmentioning

confidence: 50%

Kelvin Probe Force Microscopy under Variable Illumination: A Novel Technique To Unveil Charge Carrier Dynamics in GaN

et al. 2023

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GaN is a widely used material for optical and power devices. However, the performance of GaN-based devices is often reduced by charge trapping processes due to defect levels in the band gap. In this paper, we studied a GaN-on-silicon sample via Kelvin probe force microscopy under variable illumination. This novel methodology allows the surface photovoltage (SPV) to be followed on the GaN surface as a function of time, light intensity, and topography with nanometric resolution. The measured SPV decay after turning off the light is too slow (on the order of seconds to days) to correspond to electron−hole recombination, suggesting that it is due to charge trapping. Two processes of opposite sign contributing to SPV generation and decay were observed, indicating two different charge trapping mechanisms. In this study, we propose a model that accounts for the observed SPV behavior at different measurement temperatures. Furthermore, the contribution to the electronic behavior of possible contamination surface states is discussed.

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Section: Resultsmentioning

confidence: 50%

Kelvin Probe Force Microscopy under Variable Illumination: A Novel Technique To Unveil Charge Carrier Dynamics in GaN

et al. 2023

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“…Moreover, we emphasize that the SPV decay observed in Figure .a for points 3–5 after turning off the laser is extremely long (tens of seconds) compared to the typical carrier lifetimes found in GaN or GaN-InGaN QWs (of the order of tens of ns, even in open circuit conditions). ,,− Nonetheless, persistent photoconductivity has been reported on p-GaN − associated with Mg-related defects . This suggests that the SPV is not solely due to the generation and recombination but also involves the capture and release of charge carriers.…”

Section: Resultsmentioning

confidence: 75%

GaN/InGaN LED Sidewall Defects Analysis by Cathodoluminescence and Photosensitive Kelvin Probe Force Microscopy

González-Izquierdo,

Rochat,

Sakowski

et al. 2024

ACS Photonics

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This paper delves into the impact of sidewall defects on a GaN/ InGaN epi-LED, utilizing advanced analytical techniques with nanometric resolution: cathodoluminescence (CL) and photosensitive Kelvin probe force microscopy (KPFM). CL investigations at varying excitation energies enable an indepth study of the epi-LED by distinctly probing the top p-GaN layer and InGaN quantum wells within the mesa structure. These measurements permit the analysis of the impact of sidewall defects on the light-emitting diode (LED) light emission in different epilayers, shedding light on the phenomena affecting LED optoelectronic properties. The results reveal reduced intensities related to the GaN near-band-edge (NBE) and InGaN quantum well emission, along with an increased yellow luminescence band near the mesa edge, attributed to sidewall defects induced during the etching process. Conversely, the top p-GaN layer shows no NBE band and uniform ultraviolet luminescence line (UVL) related to Mg Ga acceptors, suggesting no effect from sidewall defects. Similarly, the surface photovoltage (SPV) measured on the top p-GaN surface by KPFM shows no significant changes near the mesa boundary. Moreover, KPFM measurements show a slow SPV decay after illumination, indicating charge trapping of holes in the surface of p-GaN, as evidenced by positive SPV and consistent with the simulations. We attribute the absence of the sidewall defects effect and the charge trapping in the p-GaN layer to high-density Mg-related defects, as supported by the uniform CL UVL emission. To ensure that sidewall defects were not masked by the high concentration of Mg impurities, we conducted photosensitive KPFM at low temperatures. At these temperatures, defects are "frozen", and different types of defects exhibit distinct detrapping time scales. The consistent behavior observed at both the center and border of the mesa structure across three different temperatures confirms that only one type of defect associated with Mg doping rather than sidewall defects is being observed. These findings suggest that the etching process used in LED fabrication does not significantly impact the role of the top p-GaN layer in LED miniaturization. Moreover, they provide crucial insights into defect-induced processes and their influence on device performance, particularly in the vicinity of LED edges. Understanding these effects is essential for fabricating high-performance microLEDs.

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Temperature dependence of current–voltage and carrier lifetime characteristics in InGaN blue light-emitting diode

2020

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Influence of temperature on different optoelectronic characteristics of InGaN light emitting diodes

Cited by 6 publications

References 56 publications

Kelvin Probe Force Microscopy under Variable Illumination: A Novel Technique To Unveil Charge Carrier Dynamics in GaN

Kelvin Probe Force Microscopy under Variable Illumination: A Novel Technique To Unveil Charge Carrier Dynamics in GaN

GaN/InGaN LED Sidewall Defects Analysis by Cathodoluminescence and Photosensitive Kelvin Probe Force Microscopy

Temperature dependence of current–voltage and carrier lifetime characteristics in InGaN blue light-emitting diode

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