INTERFACE STRUCTURE IN ARSENIDE PHOSPHIDE HETEROSTRUCTURES GROWN BY GAS-SOURCE MBE AND LOW-PRESSURE MOVPE/

We have used cross-sectional scanning tunneling microscopy (STM) to st udy interface structure in arsenide/phosphide heterostructures grown b y gas-source molecular beam epitaxy (GSMBE) and by low-pressure metalo rganic vapor phase epitaxy (LP-MOVPE). High-resolution images of GSMBE samples consisting of GaAs interrupted at 200 Angstrom intervals with a 40 s P-2 flux reveal substantial; growth-temperature-dependent inco rporation of phosphorus with nanometer-scale lateral variations in int erface structure. STM images of InGaAs/InP multiple quantum well struc tures grown by LP-MOVPE show evidence of interface asymmetry and exten sive atomic cross-incorporation at the interfaces. Data obtained by ST M have been corroborated by high-resolution x-ray diffraction and refl ection high-energy electron diffraction. Together, these studies provi de direct information about nanometer-scale grading and lateral nonuni formity of arsenide/phosphide interfaces that can occur under these gr owth conditions.