2008, Vol.18, No.3

Journal of the Korean Crystal Growth and Crystal Technology 2023 KCI Impact Factor : 0.19

pISSN : 1225-1429 / eISSN : 2234-5078
https://journal.kci.go.kr/jkcgct

Polar and non-polar GaN was grown by the HVPE on various substrates and influence of polarity has been investigated. The 10 μm thickness GaN were grown by HVPE is along A-plane (1120), C-plane (0001) and M-Plane (1010) sapphire substrate respectively. Surface properties were observed by optical microscope and atomic force microscopy. High resolution X-ray diffraction (HR-XRD) confirms the wurtzite structure. The donor band exciton peak located at ~3.4 eV and also located yellow luminescence peak at 2.2 eV. The polarity of the GaN film has a strong influence on the morphology and the optical properties.

GaN films were grown on the vertical and horizontal reactors by the hydride vapour phase epitaxy (HVPE). The structural and optical characteristics of the GaN films were investigated depending on the reactor-type. GaN epilayers were characterized by double crystal X-ray diffraction (DC-XRD), transmission electron microscopy (TEM) and photoluminescence (PL). Surface defects of two kinds of the GaN films were revealed by the wet chemical etching method, using H₃PO₄ acid at 200℃ for 8 minutes. Hexagonal etch pits were analyzed by optical microscopy and SEM. Etch pit densities were calculated to be approximately 1.4×10 7 and 1.2×106cm-² for GaN layers grown on horizontal and vertical reactors, respectively. Those results show GaN grown in the vertical reactor having a better quality of optical properties and crystallinity than that in the horizontal reactor.

Four different thin films were made by depositing PZ and PT in different stacking sequences. PZ and PT phases are preferably co-existed in sample A and C that are annealing after each coatings. The sample B and D, on the other hands, have tendency toward the PZT phase after co-firing the sample. The sample B that started from PT stacking first was more stable PZT phase than that of PZ first sample D.