Theoretical analysis of semi/non-polar InGaN/GaN light-emitting diodes grown on silicon substrates

Abstract

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-GaN side, the uniformity of distribution of carriers and radiative recombination rate for the non-polar 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.

Alteration of structural and optical properties in quaternary Al0.1In0.1Ga0.8N films using ultraviolet assisted photo-electrochemical etching route

“…Keeping pace with research and investigation carried out thus far on the III-nitrides semiconductors, stemming from binary GaN to ternary Al x Ga 1-x N and In y Ga 1-y N [11][12][13][14][15][16][17], as well as quaternary Al x In y Ga 1-x-y N [18][19][20], significance of growing optimum III-nitrides heterostructures for quantum wells with regards to the LEDs performance is unveiled.…”

Comparision between Ga- and N-polarity InGaN solar cells with gradient-In-composition intrinsic layers

“…[6][7][8] Besides, there is very strong spontaneous and piezoelectric polarization in the InGaN-based SC structure, moreover the polarization will be further enhanced with increasing In composition that can generate a large number of interface charges. [9][10][11] For the common Gapolarity SC structure along the [0001] direction, the direction of electric field from the polarization is opposite to that of the built-in electric field, which is much less favorable for car-rier collection. [12] Another alternative is to prepare SC structure on an N-polarity template.…”