Investigation of electrical, optical, structural and morphological properties of n-ZnO/AlN/p-GaN near UV-blue light emitting diodes (LED) fabricated under different sputtering

In this thesis, the electrical, optical, structural and morphological properties of n-ZnO/AlN/p-GaN near uv-blue light Emiiting Diodes (Led) fabricated under different sputtering powers were examined. In this study, we have used different thin film deposition techniques to obtain p-n junctions. Firstly, nitrite layers were deposited on Sapphire (Al2O3, with (0 0 0 1) orientation) substrates using Metal-Organic Chemical Vapor Deposition (MOCVD) technique. Then ZnO depositions were performed for the n-type layers under 25 W, 50 W, 75 W, 90 W and 100W sputtering powers with r.f. Magnetron sputtering method. The LED structure is completed by making contacts on p-GaN and n-ZnO layers. The electrical, structural, optical and morphological properties of the samples were determined by evaluating current-voltage (I-V) measurements, X-ray diffractions (XRD), Photoluminescence (PL), Electroluminescence (EL) datas and Atomic Force Microscope (AFM) results. According to the rms values of AFM results. As the sputtering power increased, grain size increased. In addition, PL peaks were observed at 422nm, 465nm, 425nm, 420 nm, 421 nm for ZnO and at 423nm for GaN layers at 25 W, 50 W, 75 W, 90 W and 100 W sputtering powers, respectively. The room temperature Electroluminescence (EL) of the LEDs showed strong violet-blue emission spectra at 455, 442, 430, 420 and 395 nm for ZnO thin films deposited at 25 W, 50 W, 75 W, 90 W and 100 W sputtering powers, respectively. The I-V curves of the LEDs showed good rectifying behavior with threshold voltages of 6,8 V, 6,4 V, 5,5 V, 3,3 V and 5,2 V for 25 W, 50 W, 75 W, 90 W and 100 W values