• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.107-112
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• 1999

The ZnSe/GaAs epilayers were grown by RF reactive sputtering. In order to obtain the optimum condition of the growth, we have studied the dependence of Ar pressure, input power of sputter, temperature of substrate, and the distande between substrate and target. Through the observation of the grown epilayer via electronic microscope, we confirmed that the layer's surface was uniform and the boundary of the substrate and the layer was well defined. The defotmation of lattice distortion and the distortion ratio were obtained by DCRC measurements. From mrasurements of photoluminescence, in the ZnSe/GaAs sample without injection of $N_2$gas, we found that the intensity of bound exciton $I_2$is stronger than that of $I_1$and the bound exiton $I_1$represents the deep acceptor level, $I_1\;^d$. On the other hand, in the ZnSe/GaAs sample with injection of$N_2$gas, the peak of$I_1$ was much higher than that of the $I_2$and the half width appeared to be narrow. We concluded that the p-type of ZnSe/GaAs epilayer was grown successfully, because of stronger peak of the bound exciton $I_1$due to the $N_2$dopping.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.1
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• pp.83-91
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• 1994

We have constructed a vertical gradient freeze (VGF) grower for GaAs single crystals 2 inch in diameter and have grown semi-insulating GaAs co-doped with Cr and In. For the co-doped crystal, the segregation coefficients of the dopants remain unchanged when compared to those doped with only Cr or In. The concentration of Cr and in atoms range from about $2{\Times}10_{16} to 3{imes}10^{17} cm^{-3}$ and $2{\Times}10^{19} to 3{\Times}10^{20} cm^{-3}$ at the seed to the tail part of the grown crystal, respectively. The averaged dislocation etch pit density is found to be less than $8000 cm^{-2}$ throughout the ingot. It is also found that there is some evidence of lattice hardening for the crystal in which the dislocation density is decreased to less than $1000 cm^{-2}$ as In concentration increases. The resistivity increases abruptly from $10^{-2}$ up to $10^8$ Ohm-cm, while the carrier concentration decreases from $10^{16}$ to $10^8 cm^{-3}$ along the growth direction of the GaAs crystal. Semi-insulating properties can be obtained above a critical concentration of Cr of about $6{\Times}10{^16} cm^{-3}$ in the crystal. The main deep levels existing in the GaAs: Cr,In sample are two electron traps at $E_C-0.81eV, E_C-0.35eV$, and two hole traps at $E_V+0.89eV, E_V+0.65eV$.

• Journal of the Korean Vacuum Society
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• v.19 no.6
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• pp.483-488
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• 2010

ZnO nano-fibrous thin films with various precursor concentrations ranging from 0.2 to 1.0 mol (M) were grown by spin-coating method and effects of the precursor concentration on surface and optical properties of the ZnO nano-ribrous thin films were investigated by using scanning electron microscopy (SEM) and photoluminescence (PL). ZnO nuclei were formed at the precursor concentration below 0.4 M and the ZnO nano-fibrous thin films were grown at the precursor concentration above 0.6 M. Further increase in the precursor concentration, the thickness of the ZnO nano-fibrous thin films is gradually increased. The intensity and the full-width at half-maximum (FWHM) of the near-band-edge emission (NBE) is increased as the precursor concentration is increased. The deep-level emission (DLE) is red-shifted as the precursor concentration is increased.