2, Nanyang Technological University, Singapore, , Singapore
Future electronic systems may employ monolithic or heterogeneous integration of various material systems such as III-V, Ge, and Si to sustain the historical trend of performance enhancement of metal-oxide-semiconductor field-effect transistors (MOSFETs) for high performance and low power logic applications and to enable hybrid circuits consisting of nano-electronic and photonic devices on the Si platform.
In this paper, we present our recent research advances in heterogeneous integration of III-V and Ge-based devices on the Si substrate. In the first part, we discuss the application of the interfacial misfit (IMF) technique which is capable of relieving strain resulting from the large lattice mismatch between two materials and minimizing the formation of threading dislocations. A very thin buffer with sub-120 nm was used prior to the growth of the high-quality channel materials with this technique. Two integration schemes will be covered including the co-integration of vertically-stacked nanowire GaSb p-channel FETs (pFETs) and InAs n-channel FETs (nFETs) as well as the co-integration of Ge pFETs and InAs nFETs on Si substrates using common contact formation, digital etch, and gate stack formation modules. In the second part, we discuss our research effort to enable large-scale monolithic integration of opto-electronic devices for low cost and multi-functional opto-electronic integrated chips (OEICs). The monolithically integrated InGaAs FETs and GaAs/AlGaAs lasers on a Si substrate will be presented. The high-quality layers for the realization of InGaAs transistors and lasers were grown using molecular beam epitaxy (MBE) on a Si substrate using Ge and GaAs buffer layers. The InGaAs FETs show good electrical characteristics with high drive current, high ION/IOFF ratio, and small subthreshold swing. Electrically pumped GaAs/AlGaAs quantum well (QW) lasers were also realized at room temperature with a spectral linewidth of less than 0.5 nm.