The Structure Optimization And Epitaxial Growth Of MQW APD

Avalanche photodiode has much more advantages working as a light receiver due to simple structure, low cost, small volume and its inherent mechanism of multiplication for what can detect the weak light signal. In order to realize high speed, high sensitivity in and low noise in avalanche photodiode, electronic ionization rate ? and hole ionization rate ? of multiplication layer material must be different from each other as much as possible. Band gap discontinuity of heterogeneous material band edge in multiple quantum well?superlattice? structure can increase electronic ionization probability rate significantly. Based on the collision ionization theory,we studied the effect of heterogeneous material superlattice structure on carrier ionization rate, in combination with band structure and material properties of superlattices, consider the reason of photoelectric detector's performance requirements grown on In P substrate working in long wavelength?1.3 1.65?m?,we designed superlattice avalanche photodiode In_0.53Ga_0.47As/ In_0.52Al_0.48 As with superlattice structure. In this paper, in order to achieve high signal to noise ratio SAPD, the research work mainly includes the following aspects:?1? In collision ionization theory we discussed the important role of threshold and introduce avalanche ionization coefficient for the description of macroscopic collision process; Detailed formulas derivation and theoretical analysis were aimed at explaining how superlattice structure affects carrier ionization rate.?2? The optimization of the device structure with semiconductor simulation tool. The low tunnel current, high multiplication factor superlattice avalanche layer was realized by analyzing the influence of different structural parameters on the device performance; According to the electric field distribution equation, we simulated the dependency of two-dimensional electric field distribution on charge device layer thickness and doping; Based on quantum efficiency and response speed, we optimized structural parameters of the absorption layer.?3? In order to get high quality epitaxial materials, conditions optimization experiment need be done for the growth of materials; Solve materials epitaxial growth experience problems for In_0.53Ga_0.47As/ In_0.52Al_0.48 As superlattice; Adjustment of the key of doping technology; Complete the epitaxial growth of superlattice avalanche photodiode device.?4? Accomplish the photoelectric characteristics test for superlattice avalanche photodiode device, and compared with the separate absorption, grade,charge, multiplication avalanche photodiode to verify the performance improvement of avalanche photodiode with superlattice structure.