Excess Noise Analysis and Simulation of Amorphous Silicon/Silicon-Carbide Separated Absorption and Multiplication Region Superlattice-like Avalanche Photodiode (SAM-SAPD)

• Main Authors: Hui-Ching Huang, 黃慧菁
• Other Authors: 貢中元
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/53997655784421954948

碩士 === 國立中興大學 === 電機工程學系所 === 94 === The separated absorption and multiplication regions superlattice-like avalanche photodiodes (SAM-SAPDs) have been designed successfully by using the combined effect of band edge discontinuity and build-in potential in p–n junction to obtain lower excess noise with higher optical gain. Avalanche multiplication is a statistical process and hence leads to carrier generation fluctuation which leads to excess noise in the avalanche multiplied photocurrent. The excess noise of SAM-SAPDs is an important issue in improving device characteristic and the relationships between excess noise factor (Fe) and mean multiplication (Me) will be described in our research. In this study, the theoretical relationships of (Fe) vs.Me for these SAM-SAPDs are simulated using the formulas presented by Shih. Several amorphous SAM-SAPD fabricated by Chiu, with different amorphous silicon-alloy layers in multiplication region are employed for discussing the relationships between Fe vs.Me. Chiu also presented experimental results of Fe vs. Me for these SAM-SAPDs. According to the optical gap diagrams of these devices, the electron ionization coefficients (α) and hole ionization coefficients (β) of each substage layer are estimated. The ratio of β to α is defined as ionization rate ratios (ks). In this study, ks is selected in theoretical calculations developed in this research to fit with the experimental results provided by Chiu. A quite consistence result is obtained to understand avalanche process in these SAM-SAPDs.