Abstract
Abstract Ternary semiconducting Ⅰ–Ⅲ–Ⅵ2 chalcopyrite are considered to be promising candidates for the application in solar energetic, optoelectronic as well as devices for processing and relaying information. CuInSe 2, CuInS2, and their multinary solid solutions are of great scientific and industrial interest because of possible application in high-efficient multi-junction tandem solar cells with conversion efficiency of 35% predicted. Reactive sputtering is one of well established methods that has many intrinsic advantages. But, the fabrication of Ⅰ–Ⅲ–Ⅵ2 thin films beyond conventional deposition methods have become extremely demanding for future photovoltaic progress to develop feasible method for large scale solar cell modules. For the purpose of preparing Ⅰ–Ⅲ–Ⅵ2 thin films with reproducible and adjustable properties, the MO-sputtering system that integrates the reactive sputter and the MOCVD has been developed. The investigations on development and amendment of novel metal-organic sputtering system were carried out. The CuInS2, CuInSe2 and CuIn(SexS(1-x))2 thin films were prepared by different targets (CuIn, CuInSe), and different experimental conditions (several parameters were selected during thin films growth: H2S flow rate, temperature, sputtering time, pressure, sulphurization, DC and RF power). A good correlation was observed between the results from the different analytical. The aim in this work was getting high quality thin films, therefore, how to change growth parameters for equilibrating the reactive rate of CVD and sputtering this two mechanisms became very important. From the results (XRD, SEM, EDS, FTIR), it had proved the excellent ability in our system to prepare high quality thin film owned very strong preferred (112) orientation and grain size reached 5μm, and practical energy band gap (about 1.4eV for CuInS2). In the RF power sputtering, the film quality was still nice even if there was no any annealing after sputtering. And the composition of film was reaching ideal. Another point was tuning Se/S ratio, there were several interesting phenomena in this experiments. The In-rich film will change to Cu-rich and crystallization become better when increase H2S flow rate, another discovery was that the Se/S change is very critical in different H2S flow rate and independent of substrate temperature (only In/Cu reached unit with higher temperature). We used another way to tune Se/S ratio that is change the time of H2S inlet, and Se/S ratio changed gradually with different conditions. And the composition was still approaching ideal. The investigation showed that system design is suitable to fabricate good quality thin films on the bas of ternary chalcopyrites of Ⅰ-Ⅲ-Ⅵ2 type for the purpose of high-efficient solar cell.