Compensation mechanism of undoped GaAs films grown by molecular beam epitaxy using an As-valved cracker cell

We have investigated GaAs films epitaxially grown by molecular beam epitaxy MBE.using a valved As-cracker source. When the cracking temperature Tc. of the As-valved cracker cell is raised, which means the dominant As species changes from As4to As2, the conduction type of the films changed from py to ny. In order to clarify the origins of the change of compensation mechanism of those GaAs films, estimations were made using electrical Hall effect.and optical photo- luminescence and far-infrared. measurements. Impurity incorporation behaviors suggested by these estimations are found to give a reasonable explanation for the change of conduction type, that is, the change of compensation mechanism. q1998 Elsevier Science B.V. All rights reserved.