2004, Vol.14, No.6

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

Shaped single crystals of Bi : Y3Ga5O12 (Bi = 0.041, 0.047 and 0.061 mol%) were grown by the micro-pulling-down method. Optical absorption spectra show an absorption band at 288 nm ascribed to the lowest energy 6s2 6s6p transition of Bi3+, while luminescence spectra demonstrate the band at 314 nm ascribed to the reverse radiative transition of the excited Bi3+ centres. At room temperature, dominant decay time component was found to be about 440 ns with a minor slower component 580 ns.

The oxide etching process was characterized in a magnetically enhanced reactive ion etching (MERIE) reactor with a CHF3/CF4 gas chemistry. A statistical experimental design plus one center point was used to characterize relationships between process factors and etch response. The etch response modeled are etch rate, etch selectivity to TiN and uniformity. Etching uniformity was improved with increasing CF4 flow ratio, increasing source power, and increasing pressure depending on source power. Characterization of via etching in CHF3/CF4 MERIE using neural networks was successfully executed giving to highly valuable information about etching mechanism and optimum etching condition. It was found that etching uniformity was closely related to surface polymerization, DC bias, TiN and uniformity.

A stoichiometric mixture of evaporating materials for CuInSe2 single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, CuInSe2 mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were 620oC and 410oC, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of CuInSe2 single crystal thin films measured with Hall effect by van der Pauw method are 9.62?016 cm-3 and 296 cm2/V톝 at 293 K, respectively. The temperature dependence of the energy band gap of the CuInSe2 obtained from the absorption spectra was well described by the Varshni's relation, Eg(T) = 1.1851 eV - (8.99?0-4 eV/K)T2/(T + 153 K). The crystal field and the spin-orbit splitting energies for the valence band of the CuInSe2 have been estimated to be 0.0087 eV and 0.2329 eV at 10 K, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the Dso definitely exists in the G6 states of the valence band of the CuInSe2. The three photocurrent peaks observed at 10 K are ascribed to the A1-, B1-, and C1-exciton peaks for n = 1.