Auger profiling studies of LPE n-AlxGa1−xAs–n-GaAs heterojunctions and the absence of rectification

Grading of the heterojunction interface has previously been proposed to explain the absence of rectification for LPE n–n heterojunctions. In this study, Auger profiles were made of LPE n-AlxGa1−xAs–n-GaAs (doped 1015 to 1016 cm−3 in both layers) which had been grown to minimize any barrier lowering due to the grading width and high carrier concentration. In a specific case, the calculated interface widths necessary to eliminate the barrier was greater than 500 Å; however, the measured interface width was less than 150 Å. Ion profiling effects such as preferential sputtering, knock-on, and substrate surface roughness would only increase the measured interface width. Although the measured interface width was much less than that required by theory to remove the barrier in the conduction band, the samples did not exhibit rectification. This indicates that the present grading model may be insufficient to explain the lack of rectification of these samples.