Self-heating effects at high pump currents in deep ultraviolet light-emitting diodes at 324 nm

Chitnis, A.; Sun, Jie; Mandavilli, V.; Pachipulusu, R.; Wu, S.; Gaevski, Mikhail; Adivarahan, V.; Zhang, J. P.; Khan, M. Asif; Sarua, Andrei; Kuball, Martin

doi:10.1063/1.1518155

Cited by 123 publications

(67 citation statements)

References 13 publications

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“…As opto-electronic devices emit light, the laser wavelength chosen for the Raman experiment needs to be as far as possible away from the light emission wavelength of the DUT. Examples in the literature include GaAs [69], GaN laser diodes [70], UV LEDs [71], amongst other device types. Figure 12 illustrates a Raman line temperature profile measured for a GaAs based laser diode.…”

Section: A Temperature Measurement For Accelerated Lifetime Testingmentioning

confidence: 99%

A Review of Raman Thermography for Electronic and Opto-Electronic Device Measurement With Submicron Spatial and Nanosecond Temporal Resolution

Kuball

Pomeroy

2016

IEEE Trans. Device Mater. Relib.

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This is the author accepted manuscript (AAM). The final published version (version of record) is available online via IEEE at http://ieeexplore.ieee.org/document/7590091. Please refer to any applicable terms of use of the publisher. University of Bristol -Explore Bristol Research General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-termsAbstract-We review the Raman thermography technique, which has been developed to determine the temperature in and around the active area of semiconductor devices with submicron spatial and nanosecond temporal resolution. This is critical for the qualification of device technology, including for accelerated lifetime reliability testing and device design optimization. Its practical use is illustrated for GaN and GaAs based high electron mobility transistors, and opto-electronic devices. We also discuss how Raman thermography is used to validate device thermal models, as well as determining the thermal conductivity of materials relevant for electronic and opto-electronic devices.

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Section: A Temperature Measurement For Accelerated Lifetime Testingmentioning

confidence: 99%

A Review of Raman Thermography for Electronic and Opto-Electronic Device Measurement With Submicron Spatial and Nanosecond Temporal Resolution

Kuball

Pomeroy

2016

IEEE Trans. Device Mater. Relib.

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“…Schwegler et al 9 (MQW) LEDs during operation using micro-Raman and another two methods. Chitnis et al 10 studied the self-heating effects in deep-UV LEDs grown on sapphire by micro-Raman. However, the details of the temperature measurements were not discussed.…”

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confidence: 99%

In Situ Temperature Measurement of GaN-Based Ultraviolet Light-Emitting Diodes by Micro-Raman Spectroscopy

Wang

Alur

et al. 2010

Journal of Elec Materi

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The junction temperatures of ultraviolet (UV) light-emitting diodes (LEDs) were determined in situ using noncontact micro-Raman spectroscopy. This method is based on the systematic downshift of the Raman peak as junction temperature rises. A calibration measurement was carried out first to establish the relation between junction temperature and the Raman peak, followed by temperature measurements as the forward current increased from 50 mA to 110 mA. A temperature rise from 27°C to 107°C was observed. We have demonstrated that micro-Raman spectroscopy is a viable technique for UV LED junction temperature determination.Due to their high power-conversion efficiency, long lifetime, and low operating cost, light-emitting diodes (LEDs) have been widely used in solid-state lighting applications. It is expected that white LEDs will gradually replace traditional lighting such as incandescent and fluorescent bulbs. 1 However, to achieve this goal, LED chips need to be designed so as to minimize heat generation and improve heat sinking, since their lifetime and luminous efficacy decrease as the junction temperature increases. 2 Therefore, it is very important to accurately determine the junction temperature of the LED during its operation. Temperature measurement methods of semiconductor devices fall into three categories: physical contact, electrical, and optical. 3 The electrical measurement method of LED temperature is based on the temperaturedependent forward voltage, derived from the Shockley diode equation and Varshni relation. 4 This method, although it provides the average junction temperature with good accuracy, lacks spatial resolution information. The existing optical methods determine the junction temperature from the slope of the high-energy portion of the electroluminescence (EL) peak 5,6 and/or the shift of the EL peak. 4 However, even these methods offer no spatial resolution and are applicable to only a single emission peak in the EL spectrum. The micro-Raman spectroscopy method, based on the measurement of the Raman peak shift upon temperature change, can be used to determine device temperature because of its high accuracy and high spatial resolution. For example, 1 lm spatial resolution and 10°C temperature accuracy were achieved by micro-Raman spectroscopy for GaN-based heterostructure fieldeffect transistors (HFETs). 7,8 The advantage of micro-Raman spectroscopy over EL-based methods is that it is also applicable to LEDs which exhibit multiple EL peaks. Temperature determination of ultraviolet (UV) LED chips by micro-Raman spectroscopy with good agreement with theory was reported previously. Schwegler et al. 9 determined the temperature of InGaN multiple-quantum-well

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“…Therefore, thermal characterization of LEDs receives much attention. The methods for steady-state measurements of the LED junction temperature [1][2][3] and phosphor temperature [4] have been developed. Also transient thermal characteristics, which are important for chip design and applications employing pulsed driving, were studied in the time domain [5,6].…”

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confidence: 99%

Thermal characterization of light‐emitting diodes in the frequency domain

Vitta

Žukauskas

2009

Phys. Status Solidi (c)

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We report on a method for measurement of thermal relaxation time constants within light‐emitting diodes (LEDs) using harmonic modulation of the driving current. The method is based on the phase shift of the forward voltage waveform in respect to that of the modulated current. The phase shift is due to the sensitivity of the forward voltage to junction temperature, which responds to the modulation of the heat generation depending on the thermal relaxation rate. The frequency dependence of the phase shift was shown to exhibit characteristic dips at angular frequencies equal to inverse thermal time constants. Such an approach for thermal characterization was demonstrated for common GaP, AlGaAs, AlInGaP, and InGaN LEDs. In particular, low‐power p‐n and double‐heterostructure LEDs as well as high‐power truncated‐inverted‐pyramid and flip‐chip LEDs were investigated. The measured thermal time constants (∼ 0.1–100 ms) were tentatively assigned to heat flows within the multilayer structure of the LEDs and collated with the numerical estimates based on thermal resistance and heat capacitance of the LED components. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Self-heating effects at high pump currents in deep ultraviolet light-emitting diodes at 324 nm

Cited by 123 publications

References 13 publications

A Review of Raman Thermography for Electronic and Opto-Electronic Device Measurement With Submicron Spatial and Nanosecond Temporal Resolution

A Review of Raman Thermography for Electronic and Opto-Electronic Device Measurement With Submicron Spatial and Nanosecond Temporal Resolution

In Situ Temperature Measurement of GaN-Based Ultraviolet Light-Emitting Diodes by Micro-Raman Spectroscopy

Thermal characterization of light‐emitting diodes in the frequency domain

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