InGaN-based multi-quantum well light-emitting diode structure with the insertion of superlattices under-layer

This paper reports on the improved crystalline quality of In0.11Ga0.89N/In0.02Ga0.98N multi-quantum well (MQW) light-emitting diode (LED) structure with the insertion of n-AlN/n-GaN multilayer (ML) and n-Al0.06Ga0.94N/n-GaN strained-layer superlattices (SLSs) cladding under-layer. The LED sample structure was epitaxially grown on Si (1 1 1) substrate by metal organic chemical vapor deposition (MOCVD) system with laminar-flow horizontal growth reactor. From X-ray rocking curves (XRCs) omega-scan (ω-scan), the n-Al0.06Ga0.94N/n-GaN SLS under-layer facilitate in improving the crystalline quality of the LED sample structures by reducing the threading dislocation density (TDD). Reciprocal space mapping (RSM) confirms the strain state of the GaN epitaxial layers. Triple axis (TA) X-ray diffraction (XRD) omega-2Theta (ω-2θ) scan reveals a higher-order fringes indicate the ML and MQW layers with sharp layer interfaces. Photoluminescence (PL) measurement of the sample with n-Al0.06Ga0.94N/n-GaN SLS under-layer shows band-to-band photon energy of 2.97 eV with narrower full-width at half-maximum (FWHM) as compared to the sample with n-Al0.03Ga0.97N under-layer. Surface morphology examination by atomic force microscopy (AFM) demonstrate smoother sample surface for the sample with n-Al0.06Ga0.94N/n-GaN SLS as compared to conventional sample without the SLS layer.