2010, Vol.20, 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

The Cu(In1 − xGax)Se2 is the absorber material for thin film solar cell with high absorption coefficient of 1 × 105cm−1. In the case of CIGS, the movable energy band gap from CuInSe2 (1.00 eV) to CuGaSe2 (1.68 eV) can be acquired while controlling Ga contain ratio. Generally, the co-evaporator method have used for development and fabrication of the CIGS absorption layer. However, this method should need many steps and lengthy deposition time with high temperature. For these reasons, in this paper, a new growth method of CIGS layer was attempted to hydride vapor transport (HVT)method. The CIGS mixed-source material reacted for HCl gas in the source zone was deposited on the substrate after transporting to growth zone. c-plane Al2O3 and undoped GaN were used as substrates for growth. The characteristics of grown samples were measured from SEM and EDS.

We report on the growth and characteristics of the structural and optical properties of InGaN nano-structures doped with antimony (Sb) as a catalyst. The use of catalyst has been explored to modify the growth and defect generation during strained layer heteroepitaxial growth. We performed the growth of the InGaN nano-structures on c-sapphire substrates using mixed-source hydride vapor phase epitaxy (HVPE). The characteristic of samples was measured by scanning electron microscope (SEM) and photoluminescence (PL). The aligning direction of c-axis of the InGaN nanostructures was changed from vertical to parallel or inclined to the surface of substrates when the Sb was added as a catalyst. The indium composition was estimated about 3.2 % in both cases of with or without the addition of Sb in the InxGa1-xN structures. From the results of InGaN nano-structures formed with the addition of Sb, we can expect the performance of optical devices would be more improved by reduced piezo-electric field if we use the InGaN nanostructures of which c-axes are aligned parallel to the substrates as an active layer.

For Ar = 5, Pr = 1.18, Le = 0.15, Pe = 2.89, Cv = 1.06, PB = 20 Torr, the effects of impurity (N2) on thermally and solutally buoyancy-driven convection (Grt = 3.46 × 104and Grs = 6.02 × 105,respectively) are theoretically investigated for further understanding and insight into an essence of thermo-solutal convection occurring in the vapor phase during the physical vapor transport. For 10 K ≤ ΔT ≤ 50 K, the crystal growth rates are intimately related and linearly proportional to a temperature difference between the source and crystal region which is a driving force for thermally buoyancy–driven convection. Moreover, both the dimensionless Peclet number (Pe) and dimensional maximum velocity magnitudes are directly and linearly proportional to ΔT. The growth rate is second order-exponentially decayed for 2 ≤ Ar ≤ 5. This is related to a finding that the effects of side walls tend to stabilize the thermo-solutal convection in the growth reactor. Finally, the growth rate is found to be first order exponentially decayed for 10 ≤ PB ≤ 200 Torr.