Nano Crystal Research Lab
- 나노 결정체 연구실
P-type oxide semiconductor Cu2O
Cuprous oxide (Cu2O) is a p-type semiconductor having a direct “dipole-forbidden” band gap of ~2.17 eV with an acceptor level 0.4 eV above the highest valence band and a direct “dipole-allowed” band gap of 2.62 eV at 4.2 K. The origin of this dual gap nature arises from its unique crystal structure, called the cuprite, which is a cubic structure with the center of inversion around each Cu atom (space group, =pnm), rendering each band of a definite parity at zone center. This in turn causes this classical semiconductor to host long-lived excitonic matter, and therefore, being ideal for studying fundamental exciton physics. Also, Cu2O has a high absorption coefficient as high as 105/cm above the dipole-allowed gap, and is non-toxic with low production cost. Therefore, when prepared into thin films, Cu2O could be utilized for several device applications such as photovoltaics, photocatalysts, nonlinear optics, thin film transistors, gas sensors, etc. In order to maximize the performance efficiency of these devices, it is necessary to engineer Cu2O thin films of high quality since the crystal quality directly influences most of key properties like carrier density, mobility, optical properties, etc.