High-speed Ingaas Pin Photodetector

Inc 53Gao47As PIN photodetectors in the range of 1.0 1.t rn-i .6 ~t rn for optical communication applications have been investigated in this dissertation work. The work has been focused on the design, processing and measurements of the photodetectors. Ino.53Gac.47As PIN photodetectors with high performance have been fabricated and their characteristics have been measured, the main works are as following: 1. The I-V, quantum efficiency, C-V as well as transient response characteristics of the photodetectors have been calculated and discussed. According to the calculated results, the structures of the photodetectors have been designed. The epitaxial structure and device pattern for the Ino.53Ga047As PIN photodetectors have been set-up for the trade-off between response speed, couple efficiency as well as quantum efficiency. A feasible layout of for the front-illuminated Ino.53Gao47As PIN photodetectors with mesa structure has been designed according to this structure. 2. Image reversal, wet etching and polyimide passivation processes for the fabrication of the photodetectors have been studied in detail to find out the optimized process conditions. A recipe for the processing of the photodetectors has been set-up. Ino.s3Gao47As PIN photodetectors have been fabricated by using this recipe. 3. The characterization techniques, as well as details of the measurement set-up for I-V, spectrum response, C-V and transient response have been discussed. Characteristics of the fabricated Ina.53Gao.47As PIN photodetectors have been measured and the results have been analyzed and discussed. Dark current of 640pA at ?V bias have been obtained for a typical photodetector, its breakdown voltage is 37V. The fabricated 1n053Ga047As PIN photodetectors show peak response wavelength at about 1.65 i m. The capacitance of about 1.4 pf has been measured at -5V bias, which is dominated by distribution parameters mainly caused by packing. The rise time of 37ps, fall time of 3Ops and FWHM of 48ps have been measured for the fabricated Ino.53Gao47As PIN photodetectors at ?OV bias, which are dominated by the RC time constant, traveling-carrier抯 diffusion at the edge of the depletion area as well as the transient response of the measurement system. A better response speed of the fabricated Inc s3Ga047As PIN photodetectors could be expected by the improvement on the transient response measurement system.