Studies of Novel Gain Materials and Resonant Light Emitters for Silicon Photonics

Microprocessor clock speeds have stagnated in the 2010s no longer keeping up with Moore's Law. With node sizes down to 7 nm it is becoming difficult to fit more transistors onto a chip due to quantum tunneling. The energy consumption of microprocessors is also a major problem for climate change and the battery life of mobile devices. To combat these problems we look to silicon photonics to provide a solution. Transmitting data optically has two main benefits, reducing the resistive heating of electrical data transfer and increasing possible data transfer bandwidth. These two properties in concert would allow a microprocessor with optical data connects to run faster and use less energy. The main problem with silicon photonics is the lack of an on-chip light source due to the poor light emission of silicon. An on-chip light source must be compatible with current CMOS fabrication processes and easy to mass produce. We seek to solve this problem by employing two-dimensional transition metal dichalcogenides (TMDs) as a laser gain material. Two-dimensional materials became a popular area of research after the "graphene revolution" pioneered by Andre Geim and Konstantin Novoselov. The techniques developed to produce atomically thin layers of graphene can be transferred to TMDs. TMDs exhibit the same strong in-plane bonding and weak interlayer van der Waals bonding as graphene, however when thinned down to monolayers they have a direct bandgap. The direct bandgap makes them good optical emitters. In this thesis I review the performance of TMD microcavity emitters in the literature and then focus on two main areas, the design and fabrication of photonic crystal cavities to produce a laser resonator and the optical and structural characterisation of 2H-MoTe2. For technological applications, large area monolayers of 2H-MoTe2 that can be grown on a device are required. I investigate the optical and structural differences between 2H-MoTe2 exfoliated from a bulk crystal and the CVD growth of MoTe2.