Applications of defect engineering in InP-based structures

Recent developments in defect engineered InP-based structures, by grown-in intrinsic defects, are reviewed. We demonstrate that n-type doping or modulation doping in InP-based structures can be realized by an intentional introduction of P-ln antisites during off-stoichiometric growth of InP at low temperatures (LT) (similar to 260-350 degrees C) by gas source molecular beam epitaxy (GS-MBE), without requiring an external shallow impurity doping source. We shall first summarize our present understanding of the mechanism responsible for the n-type conductivity of LT-InP, which is attributed to the auto-ionization of P-ln antisites via the (0/+) level resonant with the conduction band. The P-ln antisites are shown to exhibit properties meeting basic requirements for a dopant: (I) known chemical identification; (2) known electronic structure; (3) a control of doping concentration by varying growth temperature. We shah also provide a review of recent results from defect engineering, by utilizing the intrinsic n-type dopants of P,, antisites for modulation doping in InP-based heterostructures. Important issues such as doping efficiency, electron mobility, thermal stability, etc., will be addressed, in a close comparison with the extrinsically doping method by shallow dopants. (C) 2000 Elsevier Science S.A. All rights reserved.