Growth of AlxGa1−xAs parabolic quantum wells by real‐time feedback control of composition

Epitaxial AlxGa1−xAs structures whose compositions x vary continuously with thickness according to a given input function have been grown by chemical‐beam epitaxy under closed‐loop ellipsometric control. 200‐ and 500‐A parabolic quantum wells analyzed by photoreflectance and secondary‐ion mass spectrometry, respectively, show that actual compositions follow target values to within 0.02 in x. Growth of the 200‐A profile was controlled using compositions ellipsometrically determined for the outermost running 3.1 A (∼1 monolayer) of depositing material.Epitaxial AlxGa1−xAs structures whose compositions x vary continuously with thickness according to a given input function have been grown by chemical‐beam epitaxy under closed‐loop ellipsometric control. 200‐ and 500‐A parabolic quantum wells analyzed by photoreflectance and secondary‐ion mass spectrometry, respectively, show that actual compositions follow target values to within 0.02 in x. Growth of the 200‐A profile was controlled using compositions ellipsometrically determined for the outermost running 3.1 A (∼1 monolayer) of depositing material.