Effect of dislocations on luminescence properties of silicon-doped GaN grown by metalorganic chemical vapor deposition method

Abstract

Articles you may be interested inEffect of indium surfactant on stress relaxation by V-defect formation in GaN epilayers grown by metalorganic chemical vapor deposition J. Appl. Phys. 108, 093511 (2010); 10.1063/1.3487955 Erratum: "Elimination of nonuniformities in thick GaN films using metalorganic chemical vapor deposited GaN templates" [J. Elimination of nonuniformities in thick GaN films using metalorganic chemical vapor deposited GaN templates J. Appl. Phys. 90, 6011 (2001); 10.1063/1.1415363 Effect of buffer layers and stacking faults on the reduction of threading dislocation density in GaN overlayers grown by metalorganic chemical vapor depositionThe effect of dislocations on the structural and electro-optic characteristics of n-GaN has been studied. X-ray diffraction, Hall measurement, photoluminescence spectroscopy, Raman spectroscopy, and transmission electron microscopy ͑TEM͒ have been performed to understand the interdependence of strain, dislocation, and doping concentration. The most remarkable observation of the study is the blueshift observed at a doping level N D ϳ10 18 cm Ϫ3 as a result of the relaxation of strain. The TEM results reveal a higher dislocation defect density at lower doping levels (ϳ10 17 cm Ϫ3 ) than at moderate doping levels. Blueshift is found to result from the redistribution of the dislocation density due to the reduction in strain at a certain optimum doping level͑s͒. This distribution of the dislocation is such that there are virtually no dislocations at some locations, as evident from the sample MD27 with doping у10 18 cm Ϫ3 .

Properties of Si-Doped a-Plane GaN Grown with Different SiH4 Flow Rates

“…Reynolds et al found that the PL peak position in n-type GaN varied very little, which was attributed to the combined effect of screening that produces a blueshift and band gap renormalization that produces a redshift in the optical transitions. 30) Whereas, Yoshikawa et al 32) and Alam et al 33) found that with increasing Si doping concentration, the PL peak position was first redshifted and then blueshifted at above the critical doping concentration. This blueshift at high doping concentration was attributed to the band filling effect 32) or a redistribution of the dislocation density due to strain relaxation.…”

“…This blueshift at high doping concentration was attributed to the band filling effect 32) or a redistribution of the dislocation density due to strain relaxation. 33) Which mechanism dominates in the PL spectra of Si doped a-plane GaN is unclear for now and further investigation is in progress.…”

High-quality III-nitride films on conductive, transparent (2̅01)-oriented β-Ga2O3 using a GaN buffer layer

“…This broadening of the FWHM is expected as a result of high carrier concentration (at the low-energy side) introduced by Si impurities compared to undoped GaN and it can be explained by the tailing of the density of states caused by potential fluctuations introduced by the random distribution of Si dopants 39 . In addition, residual acceptors may contribute to the NBE peak broadening in the same way by introducing potential fluctuations 40 . Intensity power dependence studies show that decreasing the excitation intensity by three orders of magnitude produces no significant changes in the observed PL spectra, indicating that no band-gap filling or saturation of the defect level occurs and suggesting that these effects do not contribute to the broadening 41 .…”

Probing the relationship between structural and optical properties of Si-doped AlN

“…N edge was found to be about an order of magnitude higher than N screw . Reduction in N edge at N Si Ͼ 5 ϫ 10 18 cm −3 could be due to the bending and annihilation of these dislocations 16,23 to accommodate for the change in tensile stress ͓see Fig. 1͑b͔͒.…”