2003, Vol.13, 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

Nickel(Ni) powders were prepared from the mixture of nickel chloride and magnesium stearate by a hydrogen reduction process, and the effect of reaction temperature and the addition of magnesium stearate on the chracteristics of the powders were investigated. The effect of size reduction of nickel particles was observed in the presence of magnesium stearate owing to the inhibition of excess growth of paricles. The size reduction and the degree of agglomeration of the particles affected by the amounts of liqiud phase, which related to the increase of magnesium stearate.

In this study, Z n 0.86 M n 0.14 Te epilayer of 0.7 μ m -thickness was grown on GaAs(100) substrate by using hot wallepitaxy. GaAs(100) substrate was removed from Z n 0.86 M n 0.14 Teepilayer by the selective etching solution. The crystal structure and the lattice constant of only Z n 0.86 M n 0.14 Te epilayer were investigated to be zincblende and 6.140 \AA from X-ray diffraction pattern, respectively. Mn composition x of Z n 1 − x M n x Te epilayer was found to be 0.14 using this lattice constant and Vegard's law. The crystal quality of the epilayer was confirmed to be very good due to 256 arcsec-full-width at half-maximum of the double crystal rocking curve. The absorption spectra from the transmission ones were obtained to measure the band gap energy of Z n 0.86 M n 0.14 Te epilayer from 300 K to 10 K. With the decreasing temperature,. strong absorption regions in the absorption spectra were shifted to higher energy side and the absorption peak meaning the free exciton formation appeared near the absorption edge. The band gap energy values of Z n 0.86 M n 0.14 Te epilayer at 0 K and 300 K were found to be almost 2.4947 eV and 2.330 eV from the temperature dependence of the free exciton peak position energy of Z n 0.86 M n 0.14 Te epilayer, respectively. The free exciton peak position energy of Z n 0.86 M n 0.14 Te epilayer without GaAs substrate was larger 15.4 meV than photoluminescence peak position energy at 10 K. This energy difference between two peaks was analysed to be Stokes shift.

A stoichiometric mixture for C d I n 2 T e 4 single crystal was prepared from horizontal electric furnace. The C d I n 2 T e 4 single crystal was grown in the three-stage vertical electric furnace by using Bridgman method. The C d I n 2 T e 4 single crystal was evaluated to be tetragonal by the power method. The (001) growth plane of oriented C d I n 2 T e 4 single crystal was confirmed from back-reflection Laue patterns. The carrier density and mobility of C d I n 2 T e 4 single crystal measured with Hall effect by van der Pauw method are 8.61 × 1016 cm − 3 and 242 cm 2 /V.s at 293 K, respectively. The temperature dependence of the energy band gap of the C d I n 2 T e 4 single crystal obtained from the absorption spectra was well described by the Varshni's relation, 1.4750 e v − ( 7.69 × 10 − 3 ) e v / k ) T 2 /(T + 2147k).The crystal field and the spin-orbit splitting energies for the valence band of the C d I n 2 T e 4 single crystal have been estimated to be 0.2704 eV and 0.1465 eV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the Δ so definitely exists in the Γ 7 states of the valence band of the C d I n 2 T e 4 single crystal. The three photocurrent peaks observed at 10 K are ascribed to the A 1 − B 1 − and Cl-exciton peaks for n = 1.