Chemical bath deposition (CBD) from solution offers a simple and cost-effective route for the fabrication of high quality semiconductor thin films, without the need for high deposition temperatures, stringent vacuum or plasma generators. Chemical epitaxy is particularly advantageous for obtaining monocrystalline thin films with well-defined orientation relations with the monocrystalline substrate. Notably, understanding the chemical and physical mechanisms governing chemical epitaxy can allow us to predict and control the orientation of thin films.
Cadmium sulfide (CdS) is a II-VI semiconductor with a wide and direct band gap of 2.42 eV. In this work, we have studied the microstructure and morphology of CdS films chemically deposited on GaAs(100). The deposition of CdS on GaAs was found to be strongly influenced by several parameters, including the order of reagents addition, reagent concentrations, pH, time and temperature. The CdS films grown on GaAs(100) showed two growth orientations of (00.2)CdS||(111)GaAs and (00.2)CdS||(11-1)GaAs ; [110]CdS||[-110]GaAs orientation relationship, providing the first reported evidence for chemical epitaxy in CBD CdS on GaAs(100).
