Date of Award

Spring 1982

Degree Type

Thesis - Restricted

Degree Name

Master of Science (MS)



First Advisor

Pedrotti, Frank L.

Second Advisor

Tami, S.

Third Advisor

Feldott, Jeanette


This work is done to investigate some electrical properties of GaAs with Cr-doped and undoped substrates, implanted with Si at ion energy 120 keV, ion doses ranging from 5El2 ions/cm2 to lEl4 ions/cm2 , and to compare the dependence of electrical activation on substrate. Si ion-implanted in GaAs is a well known n-type dopant. This dopant is theoretically an amphoteric dopant. One of the objectives of this study is to investigate whether the particular preparation conditions such as substrate materials, dose and anneal temperature produce p-type activity in some instances. The electrical efficiency may depend strongly on whether implantation is into the usual Cr-doped semi-insulating GaAs substrate ~aterial or other substrates, such as undoped GaAs. This dependence will be investigated too. Samples of several different GaAs substrate materials, implanted with various doses of Si, were supplied by the Avionics Laboratory, Wright Patterson Air Force Base, Dayton, Ohio. Silicon Nitride encapsulant was used during thermal annealing, which was also performed at the Avionics Laboratory and annealed in hydrogen atmosphere at various temperatures such as 850°C, 900°C and 950°C. Electrical measurements were carried out in the Solid State Laboratory of Physics Department, Marquette University. The sheet carrier concentration, sheet resistance, Hall sheet co-efficient, Hall mobility and activation efficiency were determined for each sample by using the Van der Pauw method. Electrical characterization of both Cr-doped and undoped materials shows substantial agreement between substrates, though Cr-doped Material gives somewhat better results.