Selective etching of GaAs/Si and InP/GaAs heteroepitaxial wafer

GaAs/Si and InP/GaAs wafers growth was performed by low-pressure metal-organic chemical vapor deposition (LP-MOCVD) using a two-step growth method. The wet chemical etching methods were used to characterize the dislocations density. For the GaAs/Si wafer, the chemical etching was performed in molten KOH at temperatures about 350 degrees C and for duration about 1.5min. For the InP/GaAs wafer, the chemical etching was performed in H3PO4: HBr (2: 1) solution (Huber etchant) at temperatures about 20 degrees C and for duration about 2min. Then, the morphology of the dislocations characteristics of the etch pit density (EPD) were examined with a high-resolution field-effect scanning electron microscope (SEM). There are some ellipse dislocations pits of the GaAs/Si wafer with a density about 2.0 x 10(7) cm(-2), and sizes ranging from 700nm to 1500nm in diameter, and there are many sunken dislocations pits of the InP/GaAs wafer with a density about 2.0 x 10(8) cm(-2,) and sizes ranging from 300nm to 700nm in diameter. So the method has been accurate and convenient to show the dislocations characteristics of metamorphic GaAs/Si and InP/GaAs wafers.