Research On Avalanche Photodiodes Based On Resonant-Cavity

The research work of this thesis was supported by a grant from the Major State Basic Research Development Program of China (973 Program) "Basic Research on Compatible Heterogeneous Integration and Functional-Microstructure Assemblage for the Development of Novel Optoelectronic Devices" (No.2010CB327600),National High Technology Research and Development Program of China (863 program) (No.2007AA03Z418) and Program for Changjiang Scholars and Innovative Research Team in University (No.IRT0609).With the development of high bit rate long haul fiber-optical communication, it is required that the photo detector has much higher sensitivity and high-speed response capability. The conditionality of traditional PIN PD between quantum efficiency and response speed can be overcome by the use of resonant cavity. Because of the gain characteristic of avalanche photodiode, by putting APD inside a resonant cavity, the performance of photo-detector can be improved greatly. Based on the thinking above, this paper starts from the analysis of basic principles of APD and RCE-PD, finds a new method to improve the comprehensive performance of PD, and a new way in the fabrication process. The research results can be summarized as follows:1. Presenting a novel structural design about resonant cavity enhanced avalanche photodiodes (RCE-APD) with AlxGa1-xAs graded impact-ionization-engineered multiplication region. The noise characteristics and quantum efficiency of the avalanche photodiodes can be optimized by placing the structure of Al0.4Ga0.6As-Al0.2Ga0.8As-GaAs in the high field region and using separate absorption and multiplication region (SAM). Through theoretical analysis, when the thicknesses of Al0.4Ga0.6As, Al0.2Ga0.8As and GaAs are 28nm, 10nm and 50nm respectively, this device has achieved a low noise (κeff≈0.1), a bandwidth as high as 33 GHz in a appropriate-gain regime and a record gain-bandwidth product about 420 GHz when gain of the APD is 15.2. Studying the features of Benzocyclobutene (BCB). The innovation to stick resonant-cavity and the photo-detector in single-resonant-cavity together and stick the filtering-cavity and the. taper-cavity in one-mirror-inclined three-mirror cavity together are being presented. This innovation will simplify the fabrication process of the resonant-cavity enhanced avalanche photodiodes. The light transmission characteristic and the adhesive strength are still tested for the first time, and the use of BCB in the fabrication process of optoelectronic integrated device is improved.3. Using UV glue in the fabrication process of the flat-top steep-edge photo-detectors. Sticking the filtering-cavity and the glass slide together by the use of UV glue. The quantum efficiencies of PIN photo-detector before and after using UV glue are tested respectively, and the light transmission characteristic is still tested. By the analyses of the experiment results, some improvement methods are presented.4. Completing the fabrication of avalanche photo-detectors, learned the basic fabrication progress of PDs. Finished the fabrication of PIN photo-detectors, and a good performance photo-detector have been fabricated.