Optimum growth condition of single-crystalline undoped ZnS grown by the molecular-beam-epitaxial method using a H2S gas source

Abstract

Crystal characterization by photoluminescence and x-ray diffraction has been performed to find out the optimum growth condition of ZnS grown by the gas-source molecular-beam-epitaxial (MBE) method. In this crystal growth, important parameters are the cracking temperature of H2S gas (Tcr), the film thickness (d), both molecular-beam flux intensities (JZn and JΣS or inlet H2S gas pressure Pin), and substrate temperature (Tsub). A single crystal having a fairly high quality, whose half width of x-ray diffraction FWHM is about 0.119° (the reference value of the GaAs substrate used is 0.093°), is obtained under the growth conditions Pin=1.4×10−5 Torr (corresponding flux intensity JΣS=7×1015 cm−2 s−1), JZn/JΣS=1, and Tsub=325 °C in the case of Tcr=780 °C and d≂1 μm.

Epitaxial growth of high-quality ZnS films on sapphire and silicon by pulsed laser deposition

“…Growth can be easily controlled and optimized by adjusting the laser energy, pulse repetition rate, substrate to target distance and substrate temperature. As can be seen in figure 1, the dependence of growth rate on substrate temperature from room temperature to 680 • C is not particularly strong and the growth is relatively fast in comparison with other epitaxial techniques [5,13,16]. As mentioned earlier, this seems attributable to the fact that in PLD the kinetic energy of transporting ZnS molecules is much higher than the substrate thermal energy.…”