Date of Award

Spring 1983

Degree Type

Thesis - Restricted

Degree Name

Master of Science (MS)



First Advisor

Pedrotti, Frank L.

Second Advisor

Tani, Smio

Third Advisor

Feldott, Jeanette


Carrier concentration and mobility profiles of 120 KeV, 1E13, 3E13 and 1E14 cm-2 dose Si-ions implanted at room temperature in semi-insulating (Cr-doped) GaAs, and annealed at 850oC, have been investigated. The electrical characterization of these samples was done by using the van der Pauw Hall effect/ Sheet resistivity technique to repeatedly measure the samples after consecutive acid etches. Differential calculations were carried out for each layer. The total etched depth was measured using the Tolansky interference method. Carrier concentration and mobility profiles for each implanted dose are presinted. In almost all cases, the carrier concentration profiles are roughly gaussian, but the projected range is displaced from the value obtained from the Lindhard, Scharff and Schiott (LSS) theory. The more complicated possibilities for compensation in the case of Cr-doped substrates may lead to more scattered data and less symmetric profiles, as observed in this study. A comparison is also made between the present work and previous study on Si-ions implanted in undoped GaAs substrates used in this study. The mobility profiles are found to be roughly constant at around 3000 cm2/ V-sec, for samples with dose 1E13cm-2. The mobility increases slightly with depth for high dose samples, probably indicating more unannealed damage near the surface.



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