Electronic and Defect Structures of CuSCN
详细信息 查看全文
- 作者：John E. Jaffe ; Tiffany C. Kaspar ; Timothy C. Droubay ; Tamas Varga ; Mark E. Bowden ; Gregory J. Exarhos
- 刊名：Journal of Physical Chemistry C
- 出版年：2010
- 出版时间：May 20, 2010
- 年：2010
- 卷：114
- 期：19
- 页码：9111-9117
- 全文大小：307K
- 年卷期：v.114,no.19(May 20, 2010)
- ISSN：1932-7455
文摘
Copper thiocyanate (CuSCN) is a candidate as a transparent solid p-type conductor for optoelectronic and photovoltaic applications, such as solar cells. We calculate the band structure, bonding characteristics, and basic native defect configurations of hexagonal β-CuSCN. β-CuSCN is predicted to be an indirect-gap semiconductor with an unusual orbital character: although the highest valence bands have the expected character of Cu 3d levels hybridized with S 3p states, the conduction band minimum (at the K point of the hexagonal Brillouin zone) has mostly cyanide antibonding character. This quasi-molecular character results in some unusual properties, including that the electron effective masses are comparable to or even larger than the hole effective masses. Calculated results match well with the valence band spectrum of thin film CuSCN, although optical absorption measurements do not conclusively confirm the predicted indirect nature of the lowest transitions. The dominant p-type character of this material is explained in terms of copper vacancies; CN unit vacancies, which are also expected to be acceptors, are proposed as a mechanism to increase p-type conduction.