Abstract
This study aimed to investigate temperature dependencies at different injection currents (ICs) of the electroluminescence (EL) spectra from a green InGaN/GaN light-emitting diode (LED) based on multiple quantum wells (MQWs) grown on a Si substrate in a wide range of ICs (0.001–350 mA) and temperatures (6–350 K). The results show that the temperature-changing characteristic of the EL peak energy gradually evolves from an approximately V-shaped temperature dependence into a wave-shaped (three-step blueshift) dependence with increasing IC. Finally, it emerges as an approximately inverted V-shaped temperature dependence. The behavior reflects the fact that the emission related to InGaN is significantly influenced by the changing recombination dynamics of carriers with rising temperature or IC. This is attributed to the presence in the MQW active region of a stronger carrier localization effect across three zones with different average In contents. Moreover, with the decline of the temperature at lower ICs, the temperature behavior of the external quantum efficiency (EQE) value is dominated by the deactivated non-radiative centers. This phenomenon occurs not only in the higher temperature range but also at lower temperatures due to more In-content-induced structural defects, which are confirmed by measurements of the integrated EL intensity as well as the EQE dependence on IC.
Highlights
This study aimed to investigate temperature dependencies at different injection currents (ICs) of the electroluminescence (EL) spectra from a green InGaN/GaN light-emitting diode (LED) based on multiple quantum wells (MQWs) grown on a Si substrate in a wide range of ICs (0.001–350 mA) and temperatures (6–350 K)
This study investigated the EL spectra of a green InGaN/GaN MQWs-based LED grown on a Si substrate in wide IC (0.001–350 mA) and temperature (6–350 K) ranges
The behavior reflects the fact that the emission related to InGaN is significantly influenced by the changing recombination dynamics of carriers with increasing temperature or IC
Summary
This study aimed to investigate temperature dependencies at different injection currents (ICs) of the electroluminescence (EL) spectra from a green InGaN/GaN light-emitting diode (LED) based on multiple quantum wells (MQWs) grown on a Si substrate in a wide range of ICs (0.001–350 mA) and temperatures (6–350 K). This is attributed to the presence in the MQW active region of a stronger carrier localization effect across three zones with different average In contents. InGaN/GaN MQWs-based LEDs which emit light of longer wavelength (in the green/yellow spectral range), usually suffer from a reduction of emission efficiency (that is, the alleged green gap) These characteristics are owing to the fact that high In-content-induced composition fluctuation, or phase separation, results in the occurrence of the structural defects which serve as a non-radiative recombination center in the InGaN epilayers[6,7,8]. To determine the potential physics of light emission from InGaN/GaN MQWs-based LED emitting photons at green wavelengths, the temperature dependencies at varying ICs of electroluminescence (EL) spectra were measured and investigated by analyzing the EL peak energy, peak linewidth and EQE
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