Monolithic integration of lasers by direct growth on Si has generated much interest as a means to take advantage of the rapidly expanding capabilities of photonic integrated circuit manufacturing offered by large-area, full wafer (silicon IC manufacturing is up to 18 -diameter wafers at present) Si. Since large area InP substrates are prohibitively expensive (6 InP wafers cost about $3K), the use of large area Si substrates (upto 12 wafers) offers a pathway to significantly lower the manufacturing costs of QCLs. The direct integration of optical sources, such as quantum cascade lasers and detectors with Si-based photonics (waveguides, modulators, diffraction gratings, etc.) could also enable compact integrated lab-on-chip chemical sensing systems. In this Phase I MicroLink devices extensive experience in growth of metamorphic buffer layer for lattice constant grading will be combined with the QCL growth expertise developed at University of Wisconsin-Madison group of Prof. Luke Mawst and Prof. Dan Botez, to develop metamorphic buffer layers to reach InP lattice constant on Silicon substrates. The focus of Phase-I is to demonstrate that sufficiently low dislocation density buffer layers with low surface roughness can be grown on Si substrates. During the Phase-I base period, we will investigate the use of specially designed compositionally graded buffer layers dislocation filtering buffer layers combined with commercially available Ge on Si substrates. SL structures will be grown on such buffer layers to assess the effectiveness for the subsequent QCL growth during a Phase-I option period
Benefit: Compact laser sources emitting in the mid-wavelength infrared (MWIR) range (i.e., 4-8 mm) are currently of great interest for: stand-off spectroscopic sensing of toxic-chemical agents in defense applications, free-space communications, directed infrared countermeasures (DIRCM) and LIDAR. QCLs are ideal sources for these applications. In particular imaging and biomedical and explosive or narcotics detection. According to BCC, the market of terahertz radiation systems and devices was estimated to be $83:7 million in 2011 and is expected to reach $127 million by 2016 and is estimated to accelerate to $570 million by 2021
Keywords: QCL, QCL, Metamorphic Buffer Layers, imaging, quantum cascade lasers, THz, detection, silicon substrates, heteroepitaxy
