Band line-up transition in AlxGa1-xAs/In0.5Ga0.5P from capacitance-voltage analysis

The conduction-band discontinuity Delta E(c) of AlxGa1-xAs/In0.5Ga0.5P heterojunctions grown by liquid phase epitaxy on GaAs substrate was studied using the capacitance-voltage (C-V) characterization technique. The C-V measurements were made on a series of samples with x ranging from zero to about 0.3, The carrier profiles for the samples with x = 0 and x = 0.06 give Delta E(c) values of 90 and 40 meV, respectively, showing the type I (straddling) band line-up. For x = 0.18 and 0.29, the values of Delta E(c) were 45 and 110 meV, respectively, with the carrier profile characteristic of the type II (staggered) band line-up. From these results. Delta E(c) of the heterojunction is found to vanish at about x = 0.12. This agrees well with our previous result determined from the photoluminescence measurements. (C) 1996 American Institute of Physics.