Abstract
In this paper, the optical properties of GaN-based green light emitting diode (LED) are investigated and the internal quantum efficiency (IQE) values are measured by temperature dependent photoluminescence (TDPL) and power dependent photoluminescence (PDPL) methods. The "S-shaped” shift of peak wavelength measured at different temperature disappears gradually and the spectra broadening can be observed with increasing excitation power. The IQE calculation results of TDPL, which use the integrated intensity measured at low temperature as unity, can be modified by PDPL in order to acquire more accurate IQE values.
Highlights
GaN-based light emitting diodes (LEDs) have been widely studied for their great advantages in solid state lighting and display, among which blue LEDs, whose internal quantum efficiency (IQE)values can exceed 90%, have achieved great success attributed to the improvement of epitaxy growth technology and device structures [1,2,3,4,5,6,7,8]
The spectra at different temperature and excitation power are shown in Figure 2, in which central wavelengths (CWs) at low temperature (LT) are designated with blue lines
LED are are investigated investigated and and an an easy-toeasy-toIn implement approach to acquire more accurate values is put forward. This method is based on implement approach to acquire more accurate IQE values is put forward
Summary
GaN-based light emitting diodes (LEDs) have been widely studied for their great advantages in solid state lighting and display, among which blue LEDs, whose internal quantum efficiency (IQE)values can exceed 90%, have achieved great success attributed to the improvement of epitaxy growth technology and device structures [1,2,3,4,5,6,7,8]. Temperature dependent photoluminescence (TDPL), power dependent photoluminescence (PDPL), and time resolved photoluminescence (TRPL) are three commonly used optical methods to determine IQE values. When performing TDPL experiment, integrated intensities at different temperature are recorded and the one measured at low temperature (LT) is used as unity to obtain. IQE values, which is premised on the hypothesis that nonradiative recombination is fully frozen at LT [9,10,11]. In PDPL experiment, integrated intensities at different excitation power are recorded and the variation curves between excitation power and integrated intensities is fitted in terms of ABC model to acquire the relationships between coefficients of different recombination channels [12], which will be explained in detail later. Ultrafast lasers are used in TRPL to obtain photoluminescence (PL)
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