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 Title: An Experimental Study of Impact Ionization in Compound Semiconductors Author(s): Robbins, Virginia MacKay Doctoral Committee Chair(s): Stillman, Gregory E. Department / Program: Electrical Engineering Discipline: Electrical Engineering Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Engineering, Electronics and Electrical Abstract: Impact ionization coefficients are important parameters for the understanding of high field transport in semiconductors. Previous experimental data on impact ionization coefficients have indicated that the bandstructure can have a strong influence on the impact ionization process. In this thesis, the effects of crystallographic orientation, composition and temperature on impact ionization are reported for measurements done on InP, Al$\sb{\rm x}$Ga$\sb{\rm1-x}$As and GaAs, respectively.Photomultiplication measurements were performed on avalanche photodiodes fabricated in (111) InP. The ionization coefficients determined from these measurements are essentially the same as the ionization coefficients previously determined for (100) InP. There is no significant difference between the ratio of the ionization coefficients for the two directions over the range of electric fields observed.Photomultiplication measurements were also made on avalanche photodiodes in Al$\sb{\rm x}$Ga$\sb{\rm 1-x}$As for x = 0.1 to x = 0.4. The magnitudes of the ionization coefficients decrease with increasing x, corresponding to an increase in the threshold energy with increasing bandgap. No significant change in the ratio of the electron to hole ionization coefficients is observed with changing composition.The temperature dependence of the ionization coefficients in (100) GaAs was determined by photomultiplication measurements on avalanche photodiodes. The measurements were performed from 80 K to 500 K. The ionization coefficients decrease with increasing temperature, but no significant change in the ratio of the electron to hole ionization coefficients is observed over the range of temperature and electric fields studied. Issue Date: 1988 Type: Text Description: 102 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1988. URI: http://hdl.handle.net/2142/69388 Other Identifier(s): (UMI)AAI8815412 Date Available in IDEALS: 2014-12-15 Date Deposited: 1988
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