Use this URL to cite or link to this record in EThOS:
Title: Impact ionization in AlAs0.56Sb0.44 photodiodes
Author: Yi, Xin
ISNI:       0000 0004 9358 4032
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2020
Availability of Full Text:
Access from EThOS:
Access from Institution:
The aim of this work is to characterize the impact ionization characteristics of AlAs0.56Sb0.44 towards its use as the avalanche medium in separate absorption and multiplication avalanche photodiodes (SAM-APDs) based on InP substrate for optical communication systems. The previous studies of the AlAs0.56Sb0.44 material were only undertaken on very thin p-i-n structures where we cannot accurately estimate the impact ionization coefficient and excess noise behavior due to “dead-space” effects. In this work, much thicker AlAs0.56Sb0.44 homojunction diodes were investigated systematically. The absorption coefficient was fitted by 1-D quantum efficiency model. Comprehensive multiplication and excess noise measurements based on AlAs0.56Sb0.44 homojunction diodes over a wide range of thickness were performed at room temperature. The bulk electron and hole ionization coefficients, α and β respectively, were found to be very disparate and ‘silicon like’ at low electric fields and α > β over the whole electric field range. The ionization coefficients were determined from 220-1250 kV/cm for α and from 360-1250 kV/cm for β. The β was found to rapidly drop at the low electrical field, but the α was similar to that of InP and InAlAs. Noise measurements carried out on the thickest p-i-n structure exhibits the best reported excess noise based on InP substrate, k = 0.005 at room temperature. The SAM-APDs using AlAsSb show potentially better performance than those using InP/InAlAs as the multiplication layer.
Supervisor: David, John Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available