Epitaxial Ge Optical Devices

The epitaxial growth of thin film Ge-on-Si substrate is the key material structure for future electronic and photonic integrations. For electronic devices, the high carrier mobility in thin film Ge channel layers can improve the FET performance. For optical devices, thin film Ge is a great photonic material because of its high light efficiency, high optical absorption and pseudo-direct band gap.

 

The biaxial tensile strain in thin film Ge which is contributed by the thermal 0expansion mismatch between Ge and Si can improve the light efficiency of thin film Ge, the other advantage of Ge-on-Si. However, the lattice mismatch between Si and Ge would induce the difficulty of the growth of high quality Ge films. Amount of threading dislocation (TD) could be generated and degrade the light efficiency in thin film Ge if the interface lattice mismatch is not handled properly. Many efforts are used to decrease the TDD such as two-stage growth and thermal control.

 

Related Publications:

  1. S. -R. Jan, C. -Y. Chen, C. -H. Lee, S. -T. Chan, K. -L. Peng and C. W. Liu, “Influence of defects and interface on radiative transition of Ge” accepted by Appl. Phys. Lett., 2011.