A theoretical study of polar and semi/non-polar InGaN/GaN light-emitting diodes（LEDs） with different internal surface polarization charges, which can be grown on Si substrates, is conducted by using APSYS software. ...A theoretical study of polar and semi/non-polar InGaN/GaN light-emitting diodes（LEDs） with different internal surface polarization charges, which can be grown on Si substrates, is conducted by using APSYS software. In comparison with polar structure LEDs, the semi-polar structure exhibits a higher concentration of electrons and holes and radiative recombination rate, and its reduced built-in polarization field weakens the extent of band bending which causes the shift of peak emission wavelength. So the efficiency droop of semi-polar InGaN/GaN LEDs declines obviously and the optical power is significantly improved. In comparison with non-polar structure LEDs, although the concentration of holes and electrons as well as the radiative recombination rate of the semi-polar structure are better in the last two quantum wells（QWs） approaching the p-Ga N side, the uniformity of distribution of carriers and radiative recombination rate for the nonpolar structure is better. So the theoretical analysis indicates that the removal of the internal polarization field in the MQWs active regions for non-polar structure LEDs contributes to the uniform distribution of electrons and holes, and decreases the electron leakage. Thus it enhances the radiative recombination rate, and further improves the IQEs and optical powers, and shows the best photoelectric properties among these three structures.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.51172079)the Science and Technology Program of Guangdong Province,China(Grant Nos.2010B090400456 and 2010A081002002)+1 种基金the Science and Technology Program of Guangzhou,China(Grant No.2011J4300018)the Program for Changjiang Scholars and Innovative Research Team in Universities of China(Grant No.IRT13064)
文摘A theoretical study of polar and semi/non-polar InGaN/GaN light-emitting diodes（LEDs） with different internal surface polarization charges, which can be grown on Si substrates, is conducted by using APSYS software. In comparison with polar structure LEDs, the semi-polar structure exhibits a higher concentration of electrons and holes and radiative recombination rate, and its reduced built-in polarization field weakens the extent of band bending which causes the shift of peak emission wavelength. So the efficiency droop of semi-polar InGaN/GaN LEDs declines obviously and the optical power is significantly improved. In comparison with non-polar structure LEDs, although the concentration of holes and electrons as well as the radiative recombination rate of the semi-polar structure are better in the last two quantum wells（QWs） approaching the p-Ga N side, the uniformity of distribution of carriers and radiative recombination rate for the nonpolar structure is better. So the theoretical analysis indicates that the removal of the internal polarization field in the MQWs active regions for non-polar structure LEDs contributes to the uniform distribution of electrons and holes, and decreases the electron leakage. Thus it enhances the radiative recombination rate, and further improves the IQEs and optical powers, and shows the best photoelectric properties among these three structures.
