Gyujin Oh

Optimization of the p+-ZnTe layer for back contacts of ZnTe thin-film solar cells

We have studied the performance of ZnTe-based heterojunction diodes grown on p-GaAs substrates by using pulsed laser deposition (PLD). In the X-ray diffraction measurements, ZnTe and CdS thin films grown on p-GaAs (100) substrates appeared to have a cubic crystalline structure while the ZnO film showed a hexagonal structure. The structure of n+-ZnO/i-ZnTe/p-GaAs with insertion of a CdS buffer layer between n+-ZnO and i-ZnTe showed strong rectifying diode characteristics, and its open-circuit voltage (Voc) and short-circuit current density (Jsc) under 1,000 Wm−2 air mass 1.5 global (AM 1.5G) illumination were measured about 0.32 V and 0.61 mAcm−2, respectively. When an inserted another layer, a ZnTe:Cu layer, as a p+-layer for the contacts on p-GaAs substrate, the value of Voc and Jsc of the n+-ZnO/CdS/i-ZnTe/ZnTe:Cu/p-GaAs structure increased to 0.39 V and 0.81 mA/cm2, respectively. As the thickness of i-ZnTe were increased from 210 to 420 nm, the photoelectric conversion efficiency of the n+-ZnO/CdS/i-ZnTe/ZnTe:Cu/p-GaAs structure increased to 0.24%.