2018, Vol.28, No.2

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

In this study, we investigated the impurity effect of Ga2O3 doped thin film by simple doping method using Mg acetate solution. Both undoped Ga2O3 thin films and Mg-doped Ga2O3 thin films were grown on Si substrates at 600 and 900 o C for 30 minutes by means of a customized MOCVD method. As a result of the surface analysis, there were no obvious morphological differences by Mg impurity implantation. The surface of the thin film grown at 900 o C was rougher than those grown at 600 o C and polycrystallization was achieved. As a result of the optical property analysis, in the case of the doped sample, the overall emission peak was red shifted and the UV radiation intensity was increased. As a result of the I-V curve, the leakage current of the 600 o C growth thin film decreased by the Mg impurity and the photocurrent of the growth thin film of 900 o C increased.

Natural convection of a two dimensional laminar steady-state incompressible fluid flow in a rectangular enclosure has been investigated numerically for low aspect ratios with the physical vapor transport crystal growth. Results show that for aspect ratio (Ar = L/H) range of 0.1 ≤ Ar ≤ 1.5, with the increase in Grashof number by one order of magnitude, the total mass flux is much augmented, and is exponentially decayed with the aspect ratio. Velocity and temperature profiles are presented at the mid-width of the rectangular enclosure. It is found that the effect of Grashof number on mass transfer is less significant when the enclosure is shallow (Ar = 0.1) and the influence of aspect ratio is stranger when the enclosure is tall and the Grashof number is high. Therefore, the convective phenomena are greatly affected by the variation of aspect ratios.

Crystal growth of α-Fe 2 O 3 nanosized particles of 80~90 nm in size, which were hydrothermally prepared from 0.03 M FeCl 3 solution at 100 o C, was investigated in Pb-containing and Pb-free frit. By heating α-Fe 2 O 3 nanosized particles in two frits at 800 o C, the average diameter of particles in frits was increased to 200~210 nm and 150~160 nm, respectively, and the crystal growth due to the aggregation and sintering of several α-Fe 2 O 3 particles was observed. Formation ratios of larger particles over 100 nm in diameter were 54 % in Pb-free frit and 85 % in Pb-containing frit. After heating α-Fe 2 O 3 particles in frits at 800 o C, 7~9 nm in average diameter of pores were formed in particles. Theses pores were derived from the porous structure of original α-Fe 2 O 3 particles and confined in particles during sintering.