| 학회 | 한국재료학회 |
| 학술대회 | 2019년 가을 (10/30 ~ 11/01, 삼척 쏠비치 호텔&리조트) |
| 권호 | 25권 2호 |
| 발표분야 | G. 나노/박막 재료 분과 |
| 제목 | Tuning the electrical properties of Zn(O,S) thin films for buffer layer |
| 초록 | The buffer layer is essential for improving efficiency of thin film solar cells because thin film solar cells, devices based on PN junction, have problems with electronic band alignment and carrier recombination at interface. It means that Buffer layers can resolve the problems at the interface between P-type absorber and N-type window layer. Cadmium sulfide (CdS) is most widely used as a buffer layer in researches, but alternative material is needed due to the toxicity of cadmium. Thus, zinc oxysulfide (Zn(O,S)) is considered as a strong candidate for replacing CdS. The Zn(O,S) has larger bandgap of 2.6 to 3.8 eV than the band gap of CdS (2.4 eV) and it can be reduced the photocurrent loss by larger bandgap. Additionally, conduction band offset (CBO) between absorber and buffer layer can be ideally optimized by using the Zn(O,S). Different with CdS, Zn(O,S) is deposited by atomic layer deposition and the band offset of Zn(O,S) is tuned by changing the stoichiometry of Zn(O,S). Optimal conduction band offset difference between absorber and buffer layers is 0 to 0.4 eV. To obtain the ideal characteristics of Zn(O,S) for buffer layer, we investigated the most proper ratio of ZnO/ZnS ALD cycle. In this presentation, di-ethyl zinc (DEZ), H2O and H2S were used for ALD process of ZnO and ZnS. 100-nm thick Zn(O,S) thin films were deposited at 110°C with ZnO:ZnS cycle ratios of 5:5, 4:1, 7:1, 9:1, 14:1 and 19:1. Thermally oxidized SiO2/Si wafers and glasses were used as substrate, and the process pressure was maintained at 1.0 torr by purging with argon gas. The crystalline phase and crystallinity were identified using an X-ray diffraction analyzer. The Hall effect measurement system was used for identifying the electrical characteristics. Further, Optical properties and electronic structures were examined by ultraviolet/visible spectrophotometer (UV–vis) and ultraviolet photoelectron spectroscopy (UPS). |
| 저자 | 김종우, 최형수, 이남규, 박현우, 정찬원, 박수현, 송석휘, 권유림, 김영준, 육현우, 전형탁 |
| 소속 | 한양대 |
| 키워드 | Buffer Layer; Thin Film Solar Cells; Atomic Layer Deposition |
