Performance improvement of GaN-based light-emitting diodes grown on Si(111) substrates by controlling the reactor pressure for the GaN nucleation layer growth

GaN-based light-emitting diodes (LEDs) have been grown on Si(111) substrates with various reactor pressures for the growth of the GaN nucleation layer (NL) using metal-organic chemical vapor deposition. The influence of the reactor pressure on the GaN NLs and the properties of GaN-based LEDs grown on Si(111) substrates is investigated in detail. It is revealed that crack-free GaN films are grown on the Si(111) substrate. As the reactor pressure for GaN NLs increases from 200 to 600 Torr, the full width at half maximum values of the X-ray diffraction rocking curves for the GaN (0002) and (1 (0) over bar 12) planes decrease from 480 to 351 arcsec, and 868 to 445 arcsec, respectively, and as a result the threading dislocation density is greatly reduced, which is confirmed via the cross-sectional transmission electron microscopy measurement. Subsequently, the relationship between bending and annihilation for dislocations, and the modes for GaN NLs are elucidated. The effect of reactor pressure for the GaN NL growth on the mode of the GaN NL is also systematically studied. Furthermore, the light output power of GaN-based LEDs with GaN NLs grown at a reactor pressure of 500 Torr is greatly improved by 73.66% in comparison to that of GaN-based LEDs with GaN NLs grown at a reactor pressure of 200 Torr. This work provides a new approach for achieving highly-efficient GaN-based LEDs on Si(111) substrates.