Is blue luminescence a fingerprint for good p-type conductivity in Mg-doped GaN?
Is blue luminescence a fingerprint for good p-type conductivity in Mg-doped GaN? lead image
Gallium nitride is a semiconductor with properties ideal for LEDs and high-power electronics. Notably, to achieve p-type conductivity, GaN requires magnesium doping, which creates a blue luminescence band whose origin and role remain unclear. To help improve Mg-doped GaN growth and annealing processes, Wang et al. investigated the complex behavior of the blue luminescence.
“Is the blue luminescence an indicator for good p-type conductivity in Mg-doped GaN?” said author Xionghui Zeng. “Obviously, blue luminescence is closely related with Mg-doping.”
As the authors increased the annealing temperature, they noticed a shift in the intensity and peak position of the blue luminescence band. This indicated that at lower annealing temperatures, the band is mainly caused by a transition from a deep donor to the shallower Mg acceptor. When the annealing temperature surpasses 900 C, the deep donors decompose, and the number of holes increases as the system switches to a shallow donor with a deeper Mg acceptor. This behavior can be attributed to the material’s local crystalline microstructure.
After growing two different concentrations of Mg-doped GaN film, the researchers carried out photoluminescence measurements and evaluated the material’s electrical properties annealed at a wide range of temperatures and confirmed the dual-factor origin of the blue luminescence band.
“Our experimental results and discussions indicate that there is not necessarily a relationship between the blue luminescence band and p-type conductivity for GaN grown by metalorganic chemical vapor deposition,” Zeng said.
The group hopes to further investigate the correlation between luminescence and conductivity by looking at other techniques and conditions for growing and annealing Mg-doped GaN.
Source: “Origin of blue luminescence in Mg-doped GaN,” by Jing Wang, Xiaodan Wang, Wanzhu Shu, Xionghui Zeng, Jiafan Chen, and Ke Xu, AIP Advances (2021). The article can be accessed at https://doi.org/10.1063/5.0037047 .
