| AVS 62nd International Symposium & Exhibition | |
| Thin Film | Thursday Sessions |
| Session TF+AS+NS+SA-ThA |
| Session: | Thin Film: Growth and Characterization, Optical and Synchrotron Characterization II |
| Presenter: | Tedi Kujofsa, University of Connecticut |
| Authors: | T. Kujofsa, University of Connecticut J.E. Ayers, University of Connecticut |
| Correspondent: | Click to Email |
The inclusion of compositionally-graded metamorphic buffer layers in multilayered heterostructures allows tremendous flexibility designing novel SiGe/Si microelectronic and optical semiconductor devices. For example, advanced CMOS transistors can be fabricated on strain relaxed buffers to obtain enhanced mobility in n-channel and p-channel devices using tensile and compressive strain, respectively. While it is necessary to control the strain in the device layers, it is also desirable to fabricate these structures with low threading dislocation densities and minimum buffer thickness. Thus, understanding lattice relaxation in multilayered and compositionally-graded heterostructures is desirable to provide guidance in designing SiGe/Si devices. This work focuses on the design of the multilayered heterostructures comprising a uniform layer of Si1-xGex (device layer) deposited on a Si (001) substrate with an intermediate compositionally-graded buffer layer of Si1-xGex. The objective of this work is to study the relaxation dynamics and misfit dislocations in the device and buffer layer. We present minimum energy calculations and show that for a given device layer with fixed germanium composition and layer thickness, there exists a combination of the buffer layer thickness and compositional grading to provide tight control of the strain in the device layer. Furthermore, we give a simple model describing the strain in the device layer.