III-V semiconductors - Gallium nitride - Wide band gap semiconductors - Aluminum compounds - Binding energy - Electric fields - Light absorption - Electroabsorption modulators - Zinc sulfide;
D O I:
10.1063/1.3567921
中图分类号:
O59 [应用物理学];
学科分类号:
摘要:
Ultraviolet electroabsorption modulators based on bulk GaN films and on GaN/AlGaN multiple quantum wells were developed and characterized. In both types of devices, the absorption edge at room temperature is dominated by excitonic effects and can be strongly modified through the application of an external electric field. In the bulk devices, the applied voltage causes a broadening and quenching of the excitonic absorption, leading to enhanced transmission. In the quantum-well devices, the external field partially cancels the built-in polarization-induced electric fields in the well layers, thereby increasing the absorption. Unlike optical modulators based on smaller-bandgap zinc blende semiconductors, the bulk devices here are shown to provide similar performance levels as the quantum well devices, which is mainly a consequence of the uniquely large exciton binding energies of nitride semiconductors. (C) 2011 American Institute of Physics. [doi:10.1063/1.3567921]