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 ep itaxy (MBE) using a valved As-cracker source. When the cracking temper ature (T-c) of the As-valved cracker cell is raised, which means the d ominant As species changes from As-4 to As-2, the conduction type of t he films changed from p(-) to n(-). 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 (photoluminescen ce and far-infrared) measurements. Impurity incorporation behaviors su ggested by these estimations are found to give a reasonable explanatio n for the change of conduction type, that is, the change of compensati on mechanism. (C) 1998 Elsevier Science B.V. All rights reserved.