Next generation avalanche photodiodes: realising new potentials using nm wide avalanche regions

Each year, the flow of Internet data around the world increases exponentially. Therefore, each year, telecommunication companies must improve data management and develop new high speed optical network components. In non-coherent detection, InGaAs p-i- n diodes are used in the detector modules for 40 to 100 GB/s networks. Sparate Absorption-Multiplication (SAM) avalanche photodiodes are a major improvemnent from p-i-n diodes, in which light absorption and avalanche gain occurs in different parts of the APDs. Unfortunately, commercial SAM APDs employing InGaAs/InP, and more recently InGaAs/InAlAs, are unable to provide sufficient bandwidth with appreciable gain at 40 Gb/s and higher. This is due to their low gain-bandwidth product (GBP). SAM APDs with w < 50 nm and negligible tunnelling current can potentially raise the GBP from 200 GHz to 1 THz, boosting the performance of next-generation Tb/s Direct Detection systems. A new wide-band gap material, AlAsSb, has been chosen as a suitable candidate to replace InAlAs. In this thesis is summarised data taken from Al1-xGaxAs0.56Sb0.44 (x = 0, 0.05, 0.1, + + 0.15) p i n diode structures. It is included all results obtained for I-V, C-V, avalanche gain, spectral response, and temperature dependence of avalanche breakdown. Also, is presented a study of several alternatives when carrying out the mesa step fabrication process, in order to achieve uniform avalanche gain across a given sample.