Fabrication of CuGaSe2/Si heterostructures for solar-cell applications

• Main Authors: Chien-Ming Chen, 陳建銘
• Other Authors: Bae-Heng Tseng
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/62378035998612047542

碩士 === 國立中山大學 === 材料與光電科學學系研究所 === 104 === For the composition control and testing electric properties, polycrystalline CuGaSe2 (CGSe) films with near-stoichiometric compositions were deposited by three-source co-evaporation on glass without the substrate rotation. XRD analysis veried that the film is single phase with the chalcopyrite structure. From Cu-rich to Ga-rich regions for the film grown on a glass substrate,the film resistivities varied from 3.7x10-1 Ω‧cm to 7.4x104 Ω‧cm. Further experiments on the formation of Ohmic contacts onto CGSe films indicated that the remaining Cu-Se phase on the surface of Cu-rich CGSe could improve the contact properties for the film attached with Mo metal electrodes. Since the successful epitaxial growth should be demonstrated prior to device fabrication, Cu-rich CGSe(p-type CGSe) films were grown on (100) n-type Si wafers.XRD analysis reveal that the c-axis of tetragonal unit cell aligned parallel to the substrate surface to lower the strain energy and thus leaded to the formation of orientation domain structure. For the films grown at 550℃, the XRD peak of CGSe was broden and asymmetric indicating an interduffusion at the CGSe/Si interface. Auger depth profiling showed that a conderable amount of Si was diffused into CGSe. Considering in a Cu-rich CGSe that Si might incorporate into the lattice site of Ga and became as a donor, which could compensate the acceptor in p-type CGSe. This would seriously degrade the junction properties of p-CGSe/n-Si device structure. It is strongly suggested that a low-temperature process such as photo-assited MBE should be employed for the film growth. Keywords:Molecular beam deposition,orientation domain structure,CuGaSe2 epitaxy, CuGaSe2/Si heterojunction solar cell