Spray pyrolysis of chalcopyrite thin films

黄铜矿型CuInS_2薄膜是太阳能电池最重要的吸收材料之一。研究了CuInS_2薄膜的喷雾热分解过程。这种工艺被称为低成本薄膜工艺。本研究利用超音速喷雾热分解系统，研究了CuInS_2薄膜的成分和表面形貌。首先，我们尝试使用含有Cu源、In源和S源的混合溶液。然而，上述溶液倾向于形成白色沉淀，这不适合于喷雾沉积。为此，我们尝试了以下三种工艺：1）采用喷涂Cu源和In源的方法制备Cu-In金属薄膜。然后用H_2S气体进行硫化，形成CuInS_2薄膜。2）从元素Cu和In中蒸镀Cu-In金属薄膜。3）通过两次喷射沉积Cu-In金属薄膜和一次喷射沉积CH_3CSNH_2溶液，制备了CuInS_2薄膜。与真空蒸发法和H_2S硫化法制备的CuInS_2薄膜相比，所制备的CuInS_2薄膜由纤维状化合物组成。此外，从喷涂膜的X射线衍射光谱显示铜的氧化物以及硫化铜的存在，这是不被KCN处理去除。因此，我们必须去除这些铜化合物，才能将这种薄膜应用于太阳能电池。

Chalcopyrite CuInS_2 thin film is one of the most important material as absorbers of solar cells. We studied spray pyrolysis of the CuInS_2 thin films which used solutions containing Cu-In-and S-compounds. This process is known as a low-cost process of thin films. In this research we made a supersonic spray pyrolysis system and studied CuInS_2 thin films in their composition and surface morphology.First, we tried to use a mixed solution containing Cu-,In-,and S-sources. The above solution, however, tend to form white precipitates, which is not suitable for a spray deposition. We thus tried the following three processes.1)We deposited by spraying Cu-and In-sources to form Cu-In metallic film. Afterward, we sulfurized it by H_2S gas to from CuInS_2 thin films.2)Cu-In metallic film was evaporated from elemental Cu and In. Later, a solution containing CH_3CSNH_2 was sprayed to sulfurize a CuInS_2 thin film.3)Two spray depositions of Cu-In metallic film and a CH_3CSNH_2 solution were successively made to form a CuInS_2 thin film.We could make CuInS_2 thin films by 1-3) processes. The grown CuInS_2 films, however, consist of fiber-like compounds, which are quite different from those gown by a vacuum evaporation and H_2S sulfurization. Moreover, x-ray diffraction spectra from sprayed film show the existence of Cu oxide as well as Cu sulfide, which are not removed by KCN treatment. We, thus, have to remove those Cu compounds to apply this film for solar cells.